Release Notes for BIND Version 9.11.37

Introduction

BIND 9.11 (Extended Support Version) is a stable branch of BIND. This
document summarizes significant changes since the last production release
on that branch.

Please see the file CHANGES for a more detailed list of changes and bug
fixes.

Download

The latest versions of BIND 9 software can always be found at https://
www.isc.org/download/. There you will find additional information about
each release, source code, and pre-compiled versions for Microsoft Windows
operating systems.

License Change

With the release of BIND 9.11.0, ISC changed to the open source license
for BIND from the ISC license to the Mozilla Public License (MPL 2.0).

The MPL-2.0 license requires that if you make changes to licensed software
(e.g. BIND) and distribute them outside your organization, that you
publish those changes under that same license. It does not require that
you publish or disclose anything other than the changes you made to our
software.

This requirement will not affect anyone who is using BIND, with or without
modifications, without redistributing it, nor anyone redistributing it
without changes. Therefore, this change will be without consequence for
most individuals and organizations who are using BIND.

Those unsure whether or not the license change affects their use of BIND,
or who wish to discuss how to comply with the license may contact ISC at
https://www.isc.org/mission/contact/.

Notes for BIND 9.11.37

Security Fixes

  • The rules for acceptance of records into the cache have been tightened
    to prevent the possibility of poisoning if forwarders send records
    outside the configured bailiwick. (CVE-2021-25220)

    ISC would like to thank Xiang Li, Baojun Liu, and Chaoyi Lu from
    Network and Information Security Lab, Tsinghua University, and
    Changgen Zou from Qi An Xin Group Corp. for bringing this
    vulnerability to our attention. [GL #2950]

Notes for BIND 9.11.36

Security Fixes

  • The lame-ttl option controls how long named caches certain types of
    broken responses from authoritative servers (see the security advisory
    for details). This caching mechanism could be abused by an attacker to
    significantly degrade resolver performance. The vulnerability has been
    mitigated by changing the default value of lame-ttl to 0 and
    overriding any explicitly set value with 0, effectively disabling this
    mechanism altogether. ISC's testing has determined that doing that has
    a negligible impact on resolver performance while also preventing
    abuse. Administrators may observe more traffic towards servers issuing
    certain types of broken responses than in previous BIND 9 releases,
    depending on client query patterns. (CVE-2021-25219)

    ISC would like to thank Kishore Kumar Kothapalli of Infoblox for
    bringing this vulnerability to our attention. [GL #2899]

Notes for BIND 9.11.35

Security Fixes

  • named failed to check the opcode of responses when performing zone
    refreshes, stub zone updates, and UPDATE forwarding. This could lead
    to an assertion failure under certain conditions and has been
    addressed by rejecting responses whose opcode does not match the
    expected value. [GL #2762]

Notes for BIND 9.11.34

This maintenance release of BIND 9.11 contains no significant changes,
although some minor updates have been made (for example, to fix build
issues on Solaris 11).

Notes for BIND 9.11.33

This maintenance release of BIND 9.11 contains no significant changes,
although some minor updates have been made (for example, to eliminate
compiler warnings emitted by GCC 11).

Notes for BIND 9.11.32

Feature Changes

  • DNSSEC responses containing NSEC3 records with iteration counts
    greater than 150 are now treated as insecure. [GL #2445]

  • The maximum supported number of NSEC3 iterations that can be
    configured for a zone has been reduced to 150. [GL #2642]

  • The implementation of the ZONEMD RR type has been updated to match RFC
    8976. [GL #2658]

Notes for BIND 9.11.31

Security Fixes

  • A malformed incoming IXFR transfer could trigger an assertion failure
    in named, causing it to quit abnormally. (CVE-2021-25214)

    ISC would like to thank Greg Kuechle of SaskTel for bringing this
    vulnerability to our attention. [GL #2467]

  • named crashed when a DNAME record placed in the ANSWER section during
    DNAME chasing turned out to be the final answer to a client query.
    (CVE-2021-25215)

    ISC would like to thank Siva Kakarla for bringing this vulnerability
    to our attention. [GL #2540]

  • When a server's configuration set the tkey-gssapi-keytab or
    tkey-gssapi-credential option, a specially crafted GSS-TSIG query
    could cause a buffer overflow in the ISC implementation of SPNEGO (a
    protocol enabling negotiation of the security mechanism used for
    GSSAPI authentication). This flaw could be exploited to crash named
    binaries compiled for 64-bit platforms, and could enable remote code
    execution when named was compiled for 32-bit platforms.
    (CVE-2021-25216)

    This vulnerability was reported to us as ZDI-CAN-13347 by Trend Micro
    Zero Day Initiative. [GL #2604]

Feature Changes

  • The ISC implementation of SPNEGO was removed from BIND 9 source code.
    Instead, BIND 9 now always uses the SPNEGO implementation provided by
    the system GSSAPI library when it is built with GSSAPI support. All
    major contemporary Kerberos/GSSAPI libraries contain an implementation
    of the SPNEGO mechanism. [GL #2607]

Notes for BIND 9.11.30

The BIND 9.11.30 release was withdrawn after a backporting bug was
discovered during pre-release testing. ISC would like to acknowledge the
assistance of Natan Segal of Bluecat Networks.

Notes for BIND 9.11.29

Bug Fixes

  • An invalid direction field (not one of N, S, E, W) in a LOC record
    resulted in an INSIST failure when a zone file containing such a
    record was loaded. [GL #2499]

Notes for BIND 9.11.28

Security Fixes

  • When tkey-gssapi-keytab or tkey-gssapi-credential was configured, a
    specially crafted GSS-TSIG query could cause a buffer overflow in the
    ISC implementation of SPNEGO (a protocol enabling negotiation of the
    security mechanism to use for GSSAPI authentication). This flaw could
    be exploited to crash named. Theoretically, it also enabled remote
    code execution, but achieving the latter is very difficult in
    real-world conditions. (CVE-2020-8625)

    This vulnerability was responsibly reported to us as ZDI-CAN-12302 by
    Trend Micro Zero Day Initiative. [GL #2354]

Notes for BIND 9.11.27

Bug Fixes

  • Multiple threads could attempt to destroy a single RBTDB instance at
    the same time, resulting in an unpredictable but low-probability
    assertion failure in free_rbtdb(). This has been fixed. [GL #2317]

Notes for BIND 9.11.26

Feature Changes

  • The default value of max-recursion-queries was increased from 75 to
    100. Since the queries sent towards root and TLD servers are now
    included in the count (as a result of the fix for CVE-2020-8616),
    max-recursion-queries has a higher chance of being exceeded by
    non-attack queries, which is the main reason for increasing its
    default value. [GL #2305]

  • The default value of nocookie-udp-size was restored back to 4096
    bytes. Since max-udp-size is the upper bound for nocookie-udp-size,
    this change relieves the operator from having to change
    nocookie-udp-size together with max-udp-size in order to increase the
    default EDNS buffer size limit. nocookie-udp-size can still be set to
    a value lower than max-udp-size, if desired. [GL #2250]

Bug Fixes

  • Handling of missing DNS COOKIE responses over UDP was tightened by
    falling back to TCP. [GL #2275]

  • The CNAME synthesized from a DNAME was incorrectly followed when the
    QTYPE was CNAME or ANY. [GL #2280]

  • Building with native PKCS#11 support for AEP Keyper has been broken
    since BIND 9.11.22. This has been fixed. [GL #2315]

Notes for BIND 9.11.25

Bug Fixes

  • named acting as a resolver could incorrectly treat signed zones with
    no DS record at the parent as bogus. Such zones should be treated as
    insecure. This has been fixed. [GL #2236]

  • After a Negative Trust Anchor (NTA) is added, BIND performs periodic
    checks to see if it is still necessary. If BIND encountered a failure
    while creating a query to perform such a check, it attempted to
    dereference a NULL pointer, resulting in a crash. [GL #2244]

  • A problem obtaining glue records could prevent a stub zone from
    functioning properly, if the authoritative server for the zone were
    configured for minimal responses. [GL #1736]

Notes for BIND 9.11.24

Feature Changes

  • DNS Flag Day 2020: The default EDNS buffer size has been changed from
    4096 to 1232 bytes. According to measurements done by multiple
    parties, this should not cause any operational problems as most of the
    Internet "core" is able to cope with IP message sizes between
    1400-1500 bytes; the 1232 size was picked as a conservative minimal
    number that could be changed by the DNS operator to an estimated path
    MTU minus the estimated header space. In practice, the smallest MTU
    witnessed in the operational DNS community is 1500 octets, the maximum
    Ethernet payload size, so a useful default for maximum DNS/UDP payload
    size on reliable networks would be 1400 bytes. [GL #2183]

Bug Fixes

  • named reported an invalid memory size when running in an environment
    that did not properly report the number of available memory pages and/
    or the size of each memory page. [GL #2166]

  • With multiple forwarders configured, named could fail the REQUIRE
    (msg->state == (-1)) assertion in lib/dns/message.c, causing it to
    crash. This has been fixed. [GL #2124]

Notes for BIND 9.11.23

Bug Fixes

  • Parsing of LOC records was made more strict by rejecting a sole period
    (.) and/or m as a value. These changes prevent zone files using such
    values from being loaded. Handling of negative altitudes which are not
    integers was also corrected. [GL #2074]

  • Several problems found by OSS-Fuzz were fixed. (None of these are
    security issues.) [GL !3953] [GL !3975]

Notes for BIND 9.11.22

Security Fixes

  • It was possible to trigger an assertion failure when verifying the
    response to a TSIG-signed request. This was disclosed in
    CVE-2020-8622.

    ISC would like to thank Dave Feldman, Jeff Warren, and Joel Cunningham
    of Oracle for bringing this vulnerability to our attention. [GL #2028]

  • When BIND 9 was compiled with native PKCS#11 support, it was possible
    to trigger an assertion failure in code determining the number of bits
    in the PKCS#11 RSA public key with a specially crafted packet. This
    was disclosed in CVE-2020-8623.

    ISC would like to thank Lyu Chiy for bringing this vulnerability to
    our attention. [GL #2037]

  • update-policy rules of type subdomain were incorrectly treated as
    zonesub rules, which allowed keys used in subdomain rules to update
    names outside of the specified subdomains. The problem was fixed by
    making sure subdomain rules are again processed as described in the
    ARM. This was disclosed in CVE-2020-8624.

    ISC would like to thank Joop Boonen of credativ GmbH for bringing this
    vulnerability to our attention. [GL #2055]

Bug Fixes

  • Wildcard RPZ passthru rules could incorrectly be overridden by other
    rules that were loaded from RPZ zones which appeared later in the
    response-policy statement. This has been fixed. [GL #1619]

  • LMDB locking code was revised to make rndc reconfig work properly on
    FreeBSD and with LMDB >= 0.9.26. [GL #1976]

Notes for BIND 9.11.21

Bug Fixes

  • named could crash when cleaning dead nodes in lib/dns/rbtdb.c that
    were being reused. [GL #1968]

  • Properly handle missing kyua command so that make check does not fail
    unexpectedly when CMocka is installed, but Kyua is not. [GL #1950]

  • The validator could fail to accept a properly signed RRset if an
    unsupported algorithm appeared earlier in the DNSKEY RRset than a
    supported algorithm. It could also stop if it detected a malformed
    public key. [GL #1689]

Notes for BIND 9.11.20

Security Fixes

  • It was possible to trigger an INSIST failure when a zone with an
    interior wildcard label was queried in a certain pattern. This was
    disclosed in CVE-2020-8619. [GL #1111] [GL #1718]

New Features

  • dig and other tools can now print the Extended DNS Error (EDE) option
    when it appears in a request or a response. [GL #1835]

Bug Fixes

  • When fully updating the NSEC3 chain for a large zone via IXFR, a
    temporary loss of performance could be experienced on the secondary
    server when answering queries for nonexistent data that required
    DNSSEC proof of non-existence (in other words, queries that required
    the server to find and to return NSEC3 data). The unnecessary
    processing step that was causing this delay has now been removed. [GL
    #1834]

  • A data race in lib/dns/resolver.c:log_formerr() that could lead to an
    assertion failure was fixed. [GL #1808]

  • Previously, provide-ixfr no; failed to return up-to-date responses
    when the serial number was greater than or equal to the current serial
    number. [GL #1714]

  • named-checkconf -p could include spurious text in server-addresses
    statements due to an uninitialized DSCP value. This has been fixed.
    [GL #1812]

  • The ARM has been updated to indicate that the TSIG session key is
    generated when named starts, regardless of whether it is needed. [GL
    #1842]

Notes for BIND 9.11.19

Security Fixes

  • To prevent exhaustion of server resources by a maliciously configured
    domain, the number of recursive queries that can be triggered by a
    request before aborting recursion has been further limited. Root and
    top-level domain servers are no longer exempt from the
    max-recursion-queries limit. Fetches for missing name server address
    records are limited to 4 for any domain. This issue was disclosed in
    CVE-2020-8616. [GL #1388]

  • Replaying a TSIG BADTIME response as a request could trigger an
    assertion failure. This was disclosed in CVE-2020-8617. [GL #1703]

Feature Changes

  • Message IDs in inbound AXFR transfers are now checked for consistency.
    Log messages are emitted for streams with inconsistent message IDs.
    [GL #1674]

Bug Fixes

  • When running on a system with support for Linux capabilities, named
    drops root privileges very soon after system startup. This was causing
    a spurious log message, "unable to set effective uid to 0: Operation
    not permitted", which has now been silenced. [GL #1042] [GL #1090]

  • When named-checkconf -z was run, it would sometimes incorrectly set
    its exit code. It reflected the status of the last view found; if
    zone-loading errors were found in earlier configured views but not in
    the last one, the exit code indicated success. Thanks to Graham
    Clinch. [GL #1807]

  • When built without LMDB support, named failed to restart after a zone
    with a double quote (") in its name was added with rndc addzone.
    Thanks to Alberto Fernández. [GL #1695]

Notes for BIND 9.11.18

Security Fixes

  • DNS rebinding protection was ineffective when BIND 9 is configured as
    a forwarding DNS server. Found and responsibly reported by Tobias
    Klein. [GL #1574]

Known Issues

  • We have received reports that in some circumstances, receipt of an
    IXFR can cause the processing of queries to slow significantly. Some
    of these are related to RPZ processing, others appear to occur where
    there are NSEC3-related changes (such as an operator changing the
    NSEC3 salt used in the hash calculation). These are being
    investigated. [GL #1685]

Notes for BIND 9.11.17

Feature Changes

  • The configure option --with-libxml2 now uses pkg-config to detect
    libxml2 library availability. You will either have to install
    pkg-config or specify the exact path where libxml2 has been installed
    on your system. [GL #1635]

Bug Fixes

  • Fixed re-signing issues with inline zones which resulted in records
    being re-signed late or not at all.

Notes for BIND 9.11.16

Bug Fixes

  • named crashed when it was queried for a nonexistent name in the CHAOS
    class. [GL #1540]

Notes for BIND 9.11.15

Bug Fixes

  • Fixed a GeoIP2 lookup bug which was triggered when certain
    libmaxminddb versions were used. [GL #1552]

  • Fixed several possible race conditions discovered by ThreadSanitizer.

Notes for BIND 9.11.14

Bug Fixes

  • Fixed a bug that caused named to leak memory on reconfiguration when
    any GeoIP2 database was in use. [GL #1445]

  • Fixed several possible race conditions discovered by ThreadSanitizer.

Notes for BIND 9.11.13

Security Fixes

  • Set a limit on the number of concurrently served pipelined TCP
    queries. This flaw is disclosed in CVE-2019-6477. [GL #1264]

New Features

  • Added a new statistics variable tcp-highwater that reports the maximum
    number of simultaneous TCP clients BIND has handled while running. [GL
    #1206]

Notes for BIND 9.11.12

None.

Notes for BIND 9.11.11

None.

Notes for BIND 9.11.10

New Features

  • A SipHash 2-4 based DNS Cookie (RFC 7873) algorithm has been added.
    [GL #605]

    If you are running multiple DNS Servers (different versions of BIND 9
    or DNS server from multiple vendors) responding from the same IP
    address (anycast or load-balancing scenarios), you'll have to make
    sure that all the servers are configured with the same DNS Cookie
    algorithm and same Server Secret for the best performance.

  • DS records included in DNS referral messages can now be validated and
    cached immediately, reducing the number of queries needed for a DNSSEC
    validation. [GL #964]

Bug Fixes

  • Interaction between DNS64 and RPZ No Data rule (CNAME *.) could cause
    unexpected results; this has been fixed. [GL #1106]

  • named-checkconf now checks DNS64 prefixes to ensure bits 64-71 are
    zero. [GL #1159]

  • named-checkconf could crash during configuration if configured to use
    "geoip continent" ACLs with legacy GeoIP. [GL #1163]

  • named-checkconf now correctly reports a missing dnstap-output option
    when dnstap is set. [GL #1136]

  • Handle ETIMEDOUT error on connect() with a non-blocking socket. [GL
    #1133]

Notes for BIND 9.11.9

New Features

  • The new GeoIP2 API from MaxMind is now supported when BIND is compiled
    using configure --with-geoip2. The legacy GeoIP API can be used by
    compiling with configure --with-geoip instead. (Note that the
    databases for the legacy API are no longer maintained by MaxMind.)

    The default path to the GeoIP2 databases will be set based on the
    location of the libmaxminddb library; for example, if it is in /usr/
    local/lib, then the default path will be /usr/local/share/GeoIP. This
    value can be overridden in named.conf using the geoip-directory
    option.

    Some geoip ACL settings that were available with legacy GeoIP,
    including searches for netspeed, org, and three-letter ISO country
    codes, will no longer work when using GeoIP2. Supported GeoIP2
    database types are country, city, domain, isp, and as. All of the
    databases support both IPv4 and IPv6 lookups. [GL #182]

Bug Fixes

  • Glue address records were not being returned in responses to root
    priming queries; this has been corrected. [GL #1092]

Notes for BIND 9.11.8

Security Fixes

  • A race condition could trigger an assertion failure when a large
    number of incoming packets were being rejected. This flaw is disclosed
    in CVE-2019-6471. [GL #942]

Notes for BIND 9.11.7

Security Fixes

  • The TCP client quota set using the tcp-clients option could be
    exceeded in some cases. This could lead to exhaustion of file
    descriptors. This flaw is disclosed in CVE-2018-5743. [GL #615]

Feature Changes

  • When trusted-keys and managed-keys are both configured for the same
    name, or when trusted-keys is used to configure a trust anchor for the
    root zone and dnssec-validation is set to auto, automatic RFC 5011 key
    rollovers will fail.

    This combination of settings was never intended to work, but there was
    no check for it in the parser. This has been corrected; a warning is
    now logged. (In BIND 9.15 and higher this error will be fatal.) [GL
    #868]

Notes for BIND 9.11.6

Security Fixes

  • Code change #4964, intended to prevent double signatures when deleting
    an inactive zone DNSKEY in some situations, introduced a new problem
    during zone processing in which some delegation glue RRsets are
    incorrectly identified as needing RRSIGs, which are then created for
    them using the current active ZSK for the zone. In some, but not all
    cases, the newly-signed RRsets are added to the zone's NSEC/NSEC3
    chain, but incompletely -- this can result in a broken chain,
    affecting validation of proof of nonexistence for records in the zone.
    [GL #771]

  • named could crash if it managed a DNSSEC security root with
    managed-keys and the authoritative zone rolled the key to an algorithm
    not supported by BIND 9. This flaw is disclosed in CVE-2018-5745. [GL
    #780]

  • named leaked memory when processing a request with multiple Key Tag
    EDNS options present. ISC would like to thank Toshifumi Sakaguchi for
    bringing this to our attention. This flaw is disclosed in
    CVE-2018-5744. [GL #772]

  • Zone transfer controls for writable DLZ zones were not effective as
    the allowzonexfr method was not being called for such zones. This flaw
    is disclosed in CVE-2019-6465. [GL #790]

Feature Changes

  • When compiled with IDN support, the dig and the nslookup commands now
    disable IDN processing when the standard output is not a tty (e.g. not
    used by human). The command line options +idnin and +idnout need to be
    used to enable IDN processing when dig or nslookup is used from the
    shell scripts.

Notes for BIND 9.11.5

Security Fixes

  • named could crash during recursive processing of DNAME records when
    deny-answer-aliases was in use. This flaw is disclosed in
    CVE-2018-5740. [GL #387]

New Features

  • Two new update policy rule types have been added krb5-selfsub and
    ms-selfsub which allow machines with Kerberos principals to update the
    name space at or below the machine names identified in the respective
    principals.

Feature Changes

  • The rndc nta command could not differentiate between views of the same
    name but different class; this has been corrected with the addition of
    a -class option. [GL #105]

Bug Fixes

  • When a negative trust anchor was added to multiple views using rndc
    nta, the text returned via rndc was incorrectly truncated after the
    first line, making it appear that only one NTA had been added. This
    has been fixed. [GL #105]

Notes for BIND 9.11.4

Security Fixes

  • When recursion is enabled but the allow-recursion and
    allow-query-cache ACLs are not specified, they should be limited to
    local networks, but they were inadvertently set to match the default
    allow-query, thus allowing remote queries. This flaw is disclosed in
    CVE-2018-5738. [GL #309]

New Features

  • named now supports the "root key sentinel" mechanism. This enables
    validating resolvers to indicate which trust anchors are configured
    for the root, so that information about root key rollover status can
    be gathered. To disable this feature, add root-key-sentinel no; to
    named.conf.

  • Added the ability not to return a DNS COOKIE option when one is
    present in the request. To prevent a cookie being returned, add
    answer-cookie no; to named.conf. [GL #173]

    answer-cookie no is only intended as a temporary measure, for use when
    named shares an IP address with other servers that do not yet support
    DNS COOKIE. A mismatch between servers on the same address is not
    expected to cause operational problems, but the option to disable
    COOKIE responses so that all servers have the same behavior is
    provided out of an abundance of caution. DNS COOKIE is an important
    security mechanism, and should not be disabled unless absolutely
    necessary.

Removed Features

  • named will now log a warning if the old BIND now can be compiled
    against libidn2 library to add IDNA2008 support. Previously BIND only
    supported IDNA2003 using (now obsolete) idnkit-1 library.

Feature Changes

  • dig +noidnin can be used to disable IDN processing on the input domain
    name, when BIND is compiled with IDN support.

  • Multiple cookie-secret clause are now supported. The first
    cookie-secret in named.conf is used to generate new server cookies.
    Any others are used to accept old server cookies or those generated by
    other servers using the matching cookie-secret.

Bug Fixes

  • named now rejects excessively large incremental (IXFR) zone transfers
    in order to prevent possible corruption of journal files which could
    cause named to abort when loading zones. [GL #339]

  • rndc reload could cause named to leak memory if it was invoked before
    the zone loading actions from a previous rndc reload command were
    completed. [RT #47076]

Notes for BIND 9.11.3

Security Fixes

  • Addresses could be referenced after being freed during resolver
    processing, causing an assertion failure. The chances of this
    happening were remote, but the introduction of a delay in resolution
    increased them. This bug is disclosed in CVE-2017-3145. [RT #46839]

  • update-policy rules that otherwise ignore the name field now require
    that it be set to "." to ensure that any type list present is properly
    interpreted. If the name field was omitted from the rule declaration
    and a type list was present it wouldn't be interpreted as expected.

Removed Features

  • The ISC DNSSEC Lookaside Validation (DLV) service has been shut down;
    all DLV records in the dlv.isc.org zone have been removed. References
    to the service have been removed from BIND documentation. Lookaside
    validation is no longer used by default by delv. The DLV key has been
    removed from bind.keys. Setting dnssec-lookaside to auto or to use
    dlv.isc.org as a trust anchor results in a warning being issued.

  • named will now log a warning if the old root DNSSEC key is explicitly
    configured and has not been updated. [RT #43670]

Protocol Changes

  • BIND can now use the Ed25519 and Ed448 Edwards Curve DNSSEC signing
    algorithms described in RFC 8080. Note, however, that these algorithms
    must be supported in OpenSSL; currently they are only available in the
    development branch of OpenSSL at https://github.com/openssl/openssl.
    [RT #44696]

  • When parsing DNS messages, EDNS KEY TAG options are checked for
    correctness. When printing messages (for example, in dig), EDNS KEY
    TAG options are printed in readable format.

Feature Changes

  • named will no longer start or accept reconfiguration if managed-keys
    or dnssec-validation auto are in use and the managed-keys directory
    (specified by managed-keys-directory, and defaulting to the working
    directory if not specified), is not writable by the effective user ID.
    [RT #46077]

  • Previously, update-policy local; accepted updates from any source so
    long as they were signed by the locally-generated session key. This
    has been further restricted; updates are now only accepted from
    locally configured addresses. [RT #45492]

Bug Fixes

  • Attempting to validate improperly unsigned CNAME responses from secure
    zones could cause a validator loop. This caused a delay in returning
    SERVFAIL and also increased the chances of encountering the crash bug
    described in CVE-2017-3145. [RT #46839]

  • When named was reconfigured, failure of some zones to load correctly
    could leave the system in an inconsistent state; while generally
    harmless, this could lead to a crash later when using rndc addzone.
    Reconfiguration changes are now fully rolled back in the event of
    failure. [RT #45841]

  • Some header files included <isc/util.h> incorrectly as it pollutes
    with namespace with non ISC_ macros and this should only be done by
    explicitly including <isc/util.h>. This has been corrected. Some code
    may depend on <isc/util.h> being implicitly included via other header
    files. Such code should explicitly include <isc/util.h>.

  • Zones created with rndc addzone could temporarily fail to inherit the
    allow-transfer ACL set in the options section of named.conf. [RT
    #46603]

  • named failed to properly determine whether there were active KSK and
    ZSK keys for an algorithm when update-check-ksk was true (which is the
    default setting). This could leave records unsigned when rolling keys.
    [RT #46743] [RT #46754] [RT #46774]

Notes for BIND 9.11.2

Security Fixes

  • An error in TSIG handling could permit unauthorized zone transfers or
    zone updates. These flaws are disclosed in CVE-2017-3142 and
    CVE-2017-3143. [RT #45383]

  • The BIND installer on Windows used an unquoted service path, which can
    enable privilege escalation. This flaw is disclosed in CVE-2017-3141.
    [RT #45229]

  • With certain RPZ configurations, a response with TTL 0 could cause
    named to go into an infinite query loop. This flaw is disclosed in
    CVE-2017-3140. [RT #45181]

Feature Changes

  • dig +ednsopt now accepts the names for EDNS options in addition to
    numeric values. For example, an EDNS Client-Subnet option could be
    sent using dig +ednsopt=ecs:.... Thanks to John Worley of Secure64 for
    the contribution. [RT #44461]

  • Threads in named are now set to human-readable names to assist
    debugging on operating systems that support that. Threads will have
    names such as "isc-timer", "isc-sockmgr", "isc-worker0001", and so on.
    This will affect the reporting of subsidiary thread names in ps and
    top, but not the main thread. [RT #43234]

  • DiG now warns about .local queries which are reserved for Multicast
    DNS. [RT #44783]

Bug Fixes

  • Fixed a bug that was introduced in an earlier development release
    which caused multi-packet AXFR and IXFR messages to fail validation if
    not all packets contained TSIG records; this caused interoperability
    problems with some other DNS implementations. [RT #45509]

  • Reloading or reconfiguring named could fail on some platforms when
    LMDB was in use. [RT #45203]

  • Due to some incorrectly deleted code, when BIND was built with LMDB,
    zones that were deleted via rndc delzone were removed from the running
    server but were not removed from the new zone database, so that
    deletion did not persist after a server restart. This has been
    corrected. [RT #45185]

  • Semicolons are no longer escaped when printing CAA and URI records.
    This may break applications that depend on the presence of the
    backslash before the semicolon. [RT #45216]

  • AD could be set on truncated answer with no records present in the
    answer and authority sections. [RT #45140]

Notes for BIND 9.11.1

Security Fixes

  • rndc "" could trigger an assertion failure in named. This flaw is
    disclosed in (CVE-2017-3138). [RT #44924]

  • Some chaining (i.e., type CNAME or DNAME) responses to upstream
    queries could trigger assertion failures. This flaw is disclosed in
    CVE-2017-3137. [RT #44734]

  • dns64 with break-dnssec yes; can result in an assertion failure. This
    flaw is disclosed in CVE-2017-3136. [RT #44653]

  • If a server is configured with a response policy zone (RPZ) that
    rewrites an answer with local data, and is also configured for DNS64
    address mapping, a NULL pointer can be read triggering a server crash.
    This flaw is disclosed in CVE-2017-3135. [RT #44434]

  • A coding error in the nxdomain-redirect feature could lead to an
    assertion failure if the redirection namespace was served from a local
    authoritative data source such as a local zone or a DLZ instead of via
    recursive lookup. This flaw is disclosed in CVE-2016-9778. [RT #43837]

  • named could mishandle authority sections with missing RRSIGs,
    triggering an assertion failure. This flaw is disclosed in
    CVE-2016-9444. [RT #43632]

  • named mishandled some responses where covering RRSIG records were
    returned without the requested data, resulting in an assertion
    failure. This flaw is disclosed in CVE-2016-9147. [RT #43548]

  • named incorrectly tried to cache TKEY records which could trigger an
    assertion failure when there was a class mismatch. This flaw is
    disclosed in CVE-2016-9131. [RT #43522]

  • It was possible to trigger assertions when processing responses
    containing answers of type DNAME. This flaw is disclosed in
    CVE-2016-8864. [RT #43465]

  • Added the ability to specify the maximum number of records permitted
    in a zone (max-records #;). This provides a mechanism to block overly
    large zone transfers, which is a potential risk with slave zones from
    other parties, as described in CVE-2016-6170. [RT #42143]

Feature Changes

  • dnstap now stores both the local and remote addresses for all
    messages, instead of only the remote address. The default output
    format for dnstap-read has been updated to include these addresses,
    with the initiating address first and the responding address second,
    separated by "-%gt;" or "%lt;-" to indicate in which direction the
    message was sent. [RT #43595]

  • Expanded and improved the YAML output from dnstap-read -y: it now
    includes packet size and a detailed breakdown of message contents. [RT
    #43622] [RT #43642]

  • If an ACL is specified with an address prefix in which the prefix
    length is longer than the address portion (for example, 192.0.2.1/8),
    named will now log a warning. In future releases this will be a fatal
    configuration error. [RT #43367]

Bug Fixes

  • A synthesized CNAME record appearing in a response before the
    associated DNAME could be cached, when it should not have been. This
    was a regression introduced while addressing CVE-2016-8864. [RT
    #44318]

  • named could deadlock if multiple changes to NSEC/NSEC3 parameters for
    the same zone were being processed at the same time. [RT #42770]

  • named could trigger an assertion when sending NOTIFY messages. [RT
    #44019]

  • Referencing a nonexistent zone in a response-policy statement could
    cause an assertion failure during configuration. [RT #43787]

  • rndc addzone could cause a crash when attempting to add a zone with a
    type other than master or slave. Such zones are now rejected. [RT
    #43665]

  • named could hang when encountering log file names with large apparent
    gaps in version number (for example, when files exist called
    "logfile.0", "logfile.1", and "logfile.1482954169"). This is now
    handled correctly. [RT #38688]

  • If a zone was updated while named was processing a query for
    nonexistent data, it could return out-of-sync NSEC3 records causing
    potential DNSSEC validation failure. [RT #43247]

Maintenance

  • The built-in root hints have been updated to include an IPv6 address
    (2001:500:12::d0d) for G.ROOT-SERVERS.NET.

Miscellaneous Notes

  • Authoritative server support for the EDNS Client Subnet option (ECS),
    introduced in BIND 9.11.0, was based on an early version of the
    specification, and is now known to have incompatibilities with other
    ECS implementations. It is also inefficient, requiring a separate view
    for each answer, and is unable to correct for overlapping subnets in
    the configuration. It is intended for testing purposes but is not
    recommended for for production use. This was not made sufficiently
    clear in the documentation at the time of release.

Notes for BIND 9.11.0

Security Fixes

  • It was possible to trigger a assertion when rendering a message using
    a specially crafted request. This flaw is disclosed in CVE-2016-2776.
    [RT #43139]

  • getrrsetbyname with a non absolute name could trigger an infinite
    recursion bug in lwresd and named with lwres configured if when
    combined with a search list entry the resulting name is too long. This
    flaw is disclosed in CVE-2016-2775. [RT #42694]

New Features

  • A new method of provisioning secondary servers called "Catalog Zones"
    has been added. This is an implementation of
    draft-muks-dnsop-dns-catalog-zones/ .

    A catalog zone is a regular DNS zone which contains a list of "member
    zones", along with the configuration options for each of those zones.
    When a server is configured to use a catalog zone, all the zones
    listed in the catalog zone are added to the local server as slave
    zones. When the catalog zone is updated (e.g., by adding or removing
    zones, or changing configuration options for existing zones) those
    changes will be put into effect. Since the catalog zone is itself a
    DNS zone, this means configuration changes can be propagated to slaves
    using the standard AXFR/IXFR update mechanism.

    This feature should be considered experimental. It currently supports
    only basic features; more advanced features such as ACLs and TSIG keys
    are not yet supported. Example catalog zone configurations can be
    found in the Chapter 9 of the BIND Administrator Reference Manual.

    Support for master entries with TSIG keys has been added to catalog
    zones, as well as support for allow-query and allow-transfer.

  • Added an isc.rndc Python module, which allows rndc commands to be sent
    from Python programs.

  • Added support for DynDB, a new interface for loading zone data from an
    external database, developed by Red Hat for the FreeIPA project.
    (Thanks in particular to Adam Tkac and Petr Spacek of Red Hat for the
    contribution.)

    Unlike the existing DLZ and SDB interfaces, which provide a limited
    subset of database functionality within BIND - translating DNS queries
    into real-time database lookups with relatively poor performance and
    with no ability to handle DNSSEC-signed data - DynDB is able to fully
    implement and extend the database API used natively by BIND.

    A DynDB module could pre-load data from an external data source, then
    serve it with the same performance and functionality as conventional
    BIND zones, and with the ability to take advantage of database
    features not available in BIND, such as multi-master replication.

  • Fetch quotas are now compiled in by default: they no longer require
    BIND to be configured with --enable-fetchlimit, as was the case when
    the feature was introduced in BIND 9.10.3.

    These quotas limit the queries that are sent by recursive resolvers to
    authoritative servers experiencing denial-of-service attacks. They can
    both reduce the harm done to authoritative servers and also avoid the
    resource exhaustion that can be experienced by recursive servers when
    they are being used as a vehicle for such an attack.

      □ fetches-per-server limits the number of simultaneous queries that
        can be sent to any single authoritative server. The configured
        value is a starting point; it is automatically adjusted downward
        if the server is partially or completely non-responsive. The
        algorithm used to adjust the quota can be configured via the
        fetch-quota-params option.

      □ fetches-per-zone limits the number of simultaneous queries that
        can be sent for names within a single domain. (Note: Unlike
        "fetches-per-server", this value is not self-tuning.)

    Statistics counters have also been added to track the number of
    queries affected by these quotas.

  • Added support for dnstap, a fast, flexible method for capturing and
    logging DNS traffic, developed by Robert Edmonds at Farsight Security,
    Inc., whose assistance is gratefully acknowledged.

    To enable dnstap at compile time, the fstrm and protobuf-c libraries
    must be available, and BIND must be configured with --enable-dnstap.

    A new utility dnstap-read has been added to allow dnstap data to be
    presented in a human-readable format.

    rndc dnstap -roll causes dnstap output files to be rolled like log
    files -- the most recent output file is renamed with a .0 suffix, the
    next most recent with .1, etc. (Note that this only works when dnstap
    output is being written to a file, not to a UNIX domain socket.) An
    optional numerical argument specifies how many backup log files to
    retain; if not specified or set to 0, there is no limit.

    rndc dnstap -reopen simply closes and reopens the dnstap output
    channel without renaming the output file.

    For more information on dnstap, see https://dnstap.info.

  • New statistics counters have been added to track traffic sizes, as
    specified in RSSAC002. Query and response message sizes are broken up
    into ranges of histogram buckets: TCP and UDP queries of size 0-15,
    16-31, ..., 272-288, and 288+, and TCP and UDP responses of size 0-15,
    16-31, ..., 4080-4095, and 4096+. These values can be accessed via the
    XML and JSON statistics channels at, for example, http://
    localhost:8888/xml/v3/traffic or http://localhost:8888/json/v1/traffic
    .

    Statistics for RSSAC02v3 traffic-volume, traffic-sizes and
    rcode-volume reporting are now collected.

  • A new DNSSEC key management utility, dnssec-keymgr, has been added.
    This tool is meant to run unattended (e.g., under cron). It reads a
    policy definition file (default /etc/dnssec-policy.conf) and creates
    or updates DNSSEC keys as necessary to ensure that a zone's keys match
    the defined policy for that zone. New keys are created whenever
    necessary to ensure rollovers occur correctly. Existing keys' timing
    metadata is adjusted as needed to set the correct rollover period,
    prepublication interval, etc. If the configured policy changes, keys
    are corrected automatically. See the dnssec-keymgr man page for full
    details.

    Note: dnssec-keymgr depends on Python and on the Python lex/yacc
    module, PLY. The other Python-based tools, dnssec-coverage and
    dnssec-checkds, have been refactored and updated as part of this work.

    dnssec-keymgr now takes a -r randomfile option.

    (Many thanks to Sebastián Castro for his assistance in developing this
    tool at the IETF 95 Hackathon in Buenos Aires, April 2016.)

  • The serial number of a dynamically updatable zone can now be set using
    rndc signing -serial number zonename. This is particularly useful with
    inline-signing zones that have been reset. Setting the serial number
    to a value larger than that on the slaves will trigger an AXFR-style
    transfer.

  • When answering recursive queries, SERVFAIL responses can now be cached
    by the server for a limited time; subsequent queries for the same
    query name and type will return another SERVFAIL until the cache times
    out. This reduces the frequency of retries when a query is
    persistently failing, which can be a burden on recursive servers. The
    SERVFAIL cache timeout is controlled by servfail-ttl, which defaults
    to 1 second and has an upper limit of 30.

  • The new rndc nta command can now be used to set a "negative trust
    anchor" (NTA), disabling DNSSEC validation for a specific domain; this
    can be used when responses from a domain are known to be failing
    validation due to administrative error rather than because of a
    spoofing attack. NTAs are strictly temporary; by default they expire
    after one hour, but can be configured to last up to one week. The
    default NTA lifetime can be changed by setting the nta-lifetime in
    named.conf. When added, NTAs are stored in a file (viewname.nta) in
    order to persist across restarts of the named server.

  • The EDNS Client Subnet (ECS) option is now supported for authoritative
    servers; if a query contains an ECS option then ACLs containing geoip
    or ecs elements can match against the address encoded in the option.
    This can be used to select a view for a query, so that different
    answers can be provided depending on the client network.

  • The EDNS EXPIRE option has been implemented on the client side,
    allowing a slave server to set the expiration timer correctly when
    transferring zone data from another slave server.

  • A new masterfile-style zone option controls the formatting of text
    zone files: When set to full, the zone file will dumped in
    single-line-per-record format.

  • dig +ednsopt can now be used to set arbitrary EDNS options in DNS
    requests.

  • dig +ednsflags can now be used to set yet-to-be-defined EDNS flags in
    DNS requests.

  • dig +[no]ednsnegotiation can now be used enable / disable EDNS version
    negotiation.

  • dig +header-only can now be used to send queries without a question
    section.

  • dig +ttlunits causes dig to print TTL values with time-unit suffixes:
    w, d, h, m, s for weeks, days, hours, minutes, and seconds.

  • dig +zflag can be used to set the last unassigned DNS header flag bit.
    This bit is normally zero.

  • dig +dscp=value can now be used to set the DSCP code point in outgoing
    query packets.

  • dig +mapped can now be used to determine if mapped IPv4 addresses can
    be used.

  • nslookup will now look up IPv6 as well as IPv4 addresses by default.
    [RT #40420]

  • serial-update-method can now be set to date. On update, the serial
    number will be set to the current date in YYYYMMDDNN format.

  • dnssec-signzone -N date also sets the serial number to YYYYMMDDNN.

  • named -L filename causes named to send log messages to the specified
    file by default instead of to the system log.

  • The rate limiter configured by the serial-query-rate option no longer
    covers NOTIFY messages; those are now separately controlled by
    notify-rate and startup-notify-rate (the latter of which controls the
    rate of NOTIFY messages sent when the server is first started up or
    reconfigured).

  • The default number of tasks and client objects available for serving
    lightweight resolver queries have been increased, and are now
    configurable via the new lwres-tasks and lwres-clients options in
    named.conf. [RT #35857]

  • Log output to files can now be buffered by specifying buffered yes;
    when creating a channel.

  • delv +tcp will exclusively use TCP when sending queries.

  • named will now check to see whether other name server processes are
    running before starting up. This is implemented in two ways: 1) by
    refusing to start if the configured network interfaces all return
    "address in use", and 2) by attempting to acquire a lock on a file
    specified by the lock-file option or the -X command line option. The
    default lock file is /var/run/named/named.lock. Specifying none will
    disable the lock file check.

  • rndc delzone can now be applied to zones which were configured in
    named.conf; it is no longer restricted to zones which were added by
    rndc addzone. (Note, however, that this does not edit named.conf; the
    zone must be removed from the configuration or it will return when
    named is restarted or reloaded.)

  • rndc modzone can be used to reconfigure a zone, using similar syntax
    to rndc addzone.

  • rndc showzone displays the current configuration for a specified zone.

  • When BIND is built with the lmdb library (Lightning Memory-Mapped
    Database), named will store the configuration information for zones
    that are added via rndc addzone in a database, rather than in a flat
    "NZF" file. This dramatically improves performance for rndc delzone
    and rndc modzone: deleting or changing the contents of a database is
    much faster than rewriting a text file.

    On startup, if named finds an existing NZF file, it will automatically
    convert it to the new NZD database format.

    To view the contents of an NZD, or to convert an NZD back to an NZF
    file (for example, to revert back to an earlier version of BIND which
    did not support the NZD format), use the new command named-nzd2nzf [RT
    #39837]

  • Added server-side support for pipelined TCP queries. Clients may
    continue sending queries via TCP while previous queries are processed
    in parallel. Responses are sent when they are ready, not necessarily
    in the order in which the queries were received.

    To revert to the former behavior for a particular client address or
    range of addresses, specify the address prefix in the
    "keep-response-order" option. To revert to the former behavior for all
    clients, use "keep-response-order { any; };".

  • The new mdig command is a version of dig that sends multiple pipelined
    queries and then waits for responses, instead of sending one query and
    waiting the response before sending the next. [RT #38261]

  • To enable better monitoring and troubleshooting of RFC 5011 trust
    anchor management, the new rndc managed-keys can be used to check
    status of trust anchors or to force keys to be refreshed. Also, the
    managed-keys data file now has easier-to-read comments. [RT #38458]

  • An --enable-querytrace configure switch is now available to enable
    very verbose query trace logging. This option can only be set at
    compile time. This option has a negative performance impact and should
    be used only for debugging. [RT #37520]

  • A new tcp-only option can be specified in server statements to force
    named to connect to the specified server via TCP. [RT #37800]

  • The nxdomain-redirect option specifies a DNS namespace to use for
    NXDOMAIN redirection. When a recursive lookup returns NXDOMAIN, a
    second lookup is initiated with the specified name appended to the
    query name. This allows NXDOMAIN redirection data to be supplied by
    multiple zones configured on the server, or by recursive queries to
    other servers. (The older method, using a single type redirect zone,
    has better average performance but is less flexible.) [RT #37989]

  • The following types have been implemented: CSYNC, NINFO, RKEY, SINK,
    TA, TALINK.

  • A new message-compression option can be used to specify whether or not
    to use name compression when answering queries. Setting this to no
    results in larger responses, but reduces CPU consumption and may
    improve throughput. The default is yes.

  • A read-only option is now available in the controls statement to grant
    non-destructive control channel access. In such cases, a restricted
    set of rndc commands are allowed, which can report information from
    named, but cannot reconfigure or stop the server. By default, the
    control channel access is not restricted to these read-only
    operations. [RT #40498]

  • When loading a signed zone, named will now check whether an RRSIG's
    inception time is in the future, and if so, it will regenerate the
    RRSIG immediately. This helps when a system's clock needs to be reset
    backwards.

  • The new minimal-any option reduces the size of answers to UDP queries
    for type ANY by implementing one of the strategies in
    "draft-ietf-dnsop-refuse-any": returning a single arbitrarily-selected
    RRset that matches the query name rather than returning all of the
    matching RRsets. Thanks to Tony Finch for the contribution. [RT
    #41615]

  • named now provides feedback to the owners of zones which have trust
    anchors configured (trusted-keys, managed-keys, dnssec-validation
    auto; and dnssec-lookaside auto;) by sending a daily query which
    encodes the keyids of the configured trust anchors for the zone. This
    is controlled by trust-anchor-telemetry and defaults to yes.

Feature Changes

  • The logging format used for querylog has been altered. It now includes
    an additional field indicating the address in memory of the client
    object processing the query.

    The ISC DNSSEC Lookaside Validation (DLV) service is scheduled to be
    disabled in 2017. A warning is now logged when named is configured to
    use this service, either explicitly or via dnssec-lookaside auto;. [RT
    #42207]

  • The timers returned by the statistics channel (indicating current
    time, server boot time, and most recent reconfiguration time) are now
    reported with millisecond accuracy. [RT #40082]

  • Updated the compiled-in addresses for H.ROOT-SERVERS.NET and
    L.ROOT-SERVERS.NET.

  • ACLs containing geoip asnum elements were not correctly matched unless
    the full organization name was specified in the ACL (as in geoip asnum
    "AS1234 Example, Inc.";). They can now match against the AS number
    alone (as in geoip asnum "AS1234";).

  • When using native PKCS#11 cryptography (i.e., configure
    --enable-native-pkcs11) HSM PINs of up to 256 characters can now be
    used.

  • NXDOMAIN responses to queries of type DS are now cached separately
    from those for other types. This helps when using "grafted" zones of
    type forward, for which the parent zone does not contain a delegation,
    such as local top-level domains. Previously a query of type DS for
    such a zone could cause the zone apex to be cached as NXDOMAIN,
    blocking all subsequent queries. (Note: This change is only helpful
    when DNSSEC validation is not enabled. "Grafted" zones without a
    delegation in the parent are not a recommended configuration.)

  • Update forwarding performance has been improved by allowing a single
    TCP connection to be shared between multiple updates.

  • By default, nsupdate will now check the correctness of hostnames when
    adding records of type A, AAAA, MX, SOA, NS, SRV or PTR. This behavior
    can be disabled with check-names no.

  • Added support for OPENPGPKEY type.

  • The names of the files used to store managed keys and added zones for
    each view are no longer based on the SHA256 hash of the view name,
    except when this is necessary because the view name contains
    characters that would be incompatible with use as a file name. For
    views whose names do not contain forward slashes ('/'), backslashes ('
    \'), or capital letters - which could potentially cause namespace
    collision problems on case-insensitive filesystems - files will now be
    named after the view (for example, internal.mkeys or external.nzf).
    However, to ensure consistent behavior when upgrading, if a file using
    the old name format is found to exist, it will continue to be used.

  • "rndc" can now return text output of arbitrary size to the caller.
    (Prior to this, certain commands such as "rndc tsig-list" and "rndc
    zonestatus" could return truncated output.)

  • Errors reported when running rndc addzone (e.g., when a zone file
    cannot be loaded) have been clarified to make it easier to diagnose
    problems.

  • When encountering an authoritative name server whose name is an alias
    pointing to another name, the resolver treats this as an error and
    skips to the next server. Previously this happened silently; now the
    error will be logged to the newly-created "cname" log category.

  • If named is not configured to validate answers, then allow fallback to
    plain DNS on timeout even when we know the server supports EDNS. This
    will allow the server to potentially resolve signed queries when TCP
    is being blocked.

  • Large inline-signing changes should be less disruptive. Signature
    generation is now done incrementally; the number of signatures to be
    generated in each quantum is controlled by "sig-signing-signatures
    number;". [RT #37927]

  • The experimental SIT option (code point 65001) of BIND 9.10.0 through
    BIND 9.10.2 has been replaced with the COOKIE option (code point 10).
    It is no longer experimental, and is sent by default, by both named
    and dig.

    The SIT-related named.conf options have been marked as obsolete, and
    are otherwise ignored.

  • When dig receives a truncated (TC=1) response or a BADCOOKIE response
    code from a server, it will automatically retry the query using the
    server COOKIE that was returned by the server in its initial response.
    [RT #39047]

  • Retrieving the local port range from net.ipv4.ip_local_port_range on
    Linux is now supported.

  • A new nsip-wait-recurse directive has been added to RPZ, specifying
    whether to look up unknown name server IP addresses and wait for a
    response before applying RPZ-NSIP rules. The default is yes. If set to
    no, named will only apply RPZ-NSIP rules to servers whose addresses
    are already cached. The addresses will be looked up in the background
    so the rule can be applied on subsequent queries. This improves
    performance when the cache is cold, at the cost of temporary
    imprecision in applying policy directives. [RT #35009]

  • Within the response-policy option, it is now possible to configure RPZ
    rewrite logging on a per-zone basis using the log clause.

  • The default preferred glue is now the address type of the transport
    the query was received over.

  • On machines with 2 or more processors (CPU), the default value for the
    number of UDP listeners has been changed to the number of detected
    processors minus one.

  • Zone transfers now use smaller message sizes to improve message
    compression. This results in reduced network usage.

  • Added support for the AVC resource record type (Application Visibility
    and Control).

    Changed rndc reconfig behavior so that newly added zones are loaded
    asynchronously and the loading does not block the server.

  • minimal-responses now takes two new arguments: no-auth suppresses
    populating the authority section but not the additional section;
    no-auth-recursive does the same but only when answering recursive
    queries.

  • At server startup time, the queues for processing notify and zone
    refresh queries are now processed in LIFO rather than FIFO order, to
    speed up loading of newly added zones. [RT #42825]

  • When answering queries of type MX or SRV, TLSA records for the target
    name are now included in the additional section to speed up DANE
    processing. [RT #42894]

  • named can now use the TCP Fast Open mechanism on the server side, if
    supported by the local operating system. [RT #42866]

Bug Fixes

  • Fixed a crash when calling rndc stats on some Windows builds: some
    Visual Studio compilers generate code that crashes when the "%z"
    printf() format specifier is used. [RT #42380]

  • Windows installs were failing due to triggering UAC without the
    installation binary being signed.

  • A change in the internal binary representation of the RBT database
    node structure enabled a race condition to occur (especially when BIND
    was built with certain compilers or optimizer settings), leading to
    inconsistent database state which caused random assertion failures.
    [RT #42380]

End of Life

BIND 9.11 (Extended Support Version) will be supported until at least
December, 2021.

See https://kb.isc.org/docs/aa-00896 for details of ISC's software support
policy.

Thank You

Thank you to everyone who assisted us in making this release possible.
