What’s New in dnspython

2.7.0 (in development)

  • TBD


  • The Tudoor fix ate legitimate Truncated exceptions, preventing the resolver from failing over to TCP and causing the query to timeout [#1053].


  • As mentioned in the “TuDoor” paper and the associated CVE-2023-29483, the dnspython stub resolver is vulnerable to a potential DoS if a bad-in-some-way response from the right address and port forged by an attacker arrives before a legitimate one on the UDP port dnspython is using for that query.

    This release addresses the issue by adopting the recommended mitigation, which is ignoring the bad packets and continuing to listen for a legitimate response until the timeout for the query has expired.

  • Added support for the NSID EDNS option.

  • Dnspython now looks for version metadata for optional packages and will not use them if they are too old. This prevents possible exceptions when a feature like DoH is not desired in dnspython, but an old httpx is installed along with dnspython for some other purpose.

  • The DoHNameserver class now allows GET to be used instead of the default POST, and also passes source and source_port correctly to the underlying query methods.


  • Dnspython now uses hatchling for builds.

  • Asynchronous destinationless sockets now work on Windows.

  • Cython is no longer supported due to various typing issues.

  • Dnspython now explicitly canonicalizes IPv4 and IPv6 addresses. Previously it was possible for non-canonical IPv6 forms to be stored in a AAAA address, which would work correctly but possibly cause problmes if the address were used as a key in a dictionary.

  • The number of messages in a section can be retrieved with section_count().

  • Truncation preferences for messages can be specified.

  • The length of a message can be automatically prepended when rendering.

  • dns.message.create_response() automatically adds padding when required by RFC 8467.

  • The TLS verify parameter is now supported by dns.query.tls(), and the DoH and DoT Nameserver subclasses.

  • The MutableMapping used to store content in a zone may now be specified by a factory when subclassing. Factories may also be provided for writable verisons and immutable versions.

  • dns.name.Name now has predecessor() and successor() methods implementing RFC 4471.

  • QUIC has had a number of bug fixes and also now supports session tickets for faster session resumption.

  • The NSEC3 class now has a next_name() method for retrieving the next name as a dns.name.Name.

  • Windows WMI interface detection should be more robust.


  • Async queries could wait forever instead of respecting the timeout if the timeout was 0 and a packet was lost. The timeout is now respected.

  • Restore HTTP/2 support which was accidentally broken during the https refactoring done as part of 2.4.0.

  • When an inception time and lifetime are specified, the signer now sets the expiration to the inception time plus lifetime, instead of the current time plus the lifetime.


  • Importing dns.dnssecalgs without the cryptography module installed no longer causes an ImportError.

  • A number of timeout bugs with the asyncio backend have been fixed.

  • DNS-over-QUIC for the asyncio backend now works for IPv6.

  • Dnspython now enforces that the candidate DNSKEYs for DNSSEC signatures have protocol 3 and have the ZONE flag set. This is a standards compliance issue more than a security issue as the legitimate authority would have to have published the non-compliant keys as well as updated their DS record in order for the records to validate (the DS digest includes both flags and protocol). Dnspython will not make invalid keys by default, but does allow them to be created and used for testing purposes.

  • Dependency specifications for optional features in the package metadata have been improved.


  • Python 3.8 or newer is required.

  • The stub resolver now uses instances of dns.nameserver.Nameserver to represent remote recursive resolvers, and can communicate using DNS over UDP/TCP, HTTPS, TLS, and QUIC. In additional to being able to specify an IPv4, IPv6, or HTTPS URL as a nameserver, instances of dns.nameserver.Nameserver are now permitted.

  • The DNS-over-HTTPS bootstrap address no longer causes URL rewriting.

  • DNS-over-HTTPS now only uses httpx; support for requests has been dropped. A source port may now be supplied when using httpx.

  • DNSSEC zone signing with NSEC records is now supported. Thank you very much (again!) Jakob Schlyter!

  • The resolver and async resolver now have the try_ddr() method, which will try to use Discovery of Designated Resolvers (DDR) to upgrade the connection from the stub resolver to the recursive server so that it uses DNS-over-HTTPS, DNS-over-TLS, or DNS-over-QUIC. This feature is currently experimental as the standard is still in draft stage.

  • The resolver and async resolver now have the make_resolver_at() and resolve_at() functions, as a convenience for making queries to specific recursive servers.

  • Curio support has been removed.


  • Python 3.7 or newer is required.

  • Type annotations are now integrated with the source code and cover far more of the library.

  • The get_soa() method has been added to dns.zone.Zone.

  • The minimum TLS version is now 1.2.

  • EDNS padding is now supported. Messages with EDNS enabled and with a non-zero pad option will be automatically padded appropriately when converted to wire format.

  • dns.zone.from_text() and dns.zone.from_file() now have an allow_directives parameter to allow finer control over how directives in zonefiles are processed.

  • A preliminary implementation of DNS-over-QUIC has been added, and will be available if the aioquic library is present. See dns.query.quic(), dns.asyncquery.quic(), and examples/doq.py for more info. This API is subject to change in future releases. For asynchronous I/O, both asyncio and Trio are supported, but Curio is not.

  • DNSSEC signing support has been added to the dns.dnssec module, along with a number of functions to help generate DS, CDS, and CDNSKEY RRsets. Thank you very much Jakob Schlyter!

  • Curio asynchronous I/O support is deprecated as of this release and will be removed in a future release.

  • The resolver object’s nameserver field is planned to become a property in dnspython 2.4. Writing to this field other than by direct assignment is deprecated, and so is depending on the mutability and form of the iterable returned when it is read.


This release has no new features, but fixes the following issues:

  • dns.zone.from_text failed if relativize was False and an origin was specified in the parameters.

  • A number of types permitted an empty “rest of the rdata”.

  • L32, L64, LP, and NID were missing from dns/rdtypes/ANY/__init__.py

  • The type definition for dns.resolver.resolve_address() was incorrect.

  • dns/win32util.py erroneously had the executable bit set.

  • The type definition for a number of asynchronous query routines was missing the default of None for the backend parameter.

  • dns/tsigkeyring.py didn’t import dns.tsig.

  • A number of rdata types that have a “rest of the line” behavior for the last field of the rdata erroneously permitted an empty string.

  • Timeout intervals are no longer reported with absurd precision in exception text.


  • SVCB and HTTPS records have been updated to track the evolving draft standard.

  • The ZONEMD type has been added.

  • The resolver now returns a LifetimeTimeout exception which includes an error trace like the NoNameservers exception. This class is a subclass of dns.exception.Timeout for backwards compatibility.

  • DNS-over-HTTPS will try to use HTTP/2 if the httpx and h2 packages are installed.

  • DNS-over-HTTPS is now supported for asynchronous queries and resolutions.

  • dns.zonefile.read_rrsets() has been added, which allows rrsets in zonefile format, or a restrition of it, to be read. This function is useful for applications that want to read DNS data in text format, but do not want to use a Zone.

  • On Windows systems, if the WMI module is available, the resolver will retrieve the nameserver from WMI instead of trying to figure it out by reading the registry. This may lead to more accurate results in some cases.

  • The CERT rdatatype now supports certificate types IPKIX, ISPKI, IPGP, ACPKIX, and IACPKIX.

  • The CDS rdatatype now allows digest type 0.

  • Dnspython zones now enforces that a node is either a CNAME node or an “other data” node. A CNAME node contains only CNAME, RRSIG(CNAME), NSEC, RRSIG(NSEC), NSEC3, or RRSIG(NSEC3) rdatasets. An “other data” node contains any rdataset other than a CNAME or RRSIG(CNAME) rdataset. The enforcement is “last update wins”. For example, if you have a node which contains a CNAME rdataset, and then add an MX rdataset to it, then the CNAME rdataset will be deleted. Likewise if you have a node containing an MX rdataset and add a CNAME rdataset, the MX rdataset will be deleted.

  • Extended DNS Errors, as specified in RFC 8914, are now supported.


  • End-of-line comments are now associated with rdata when read from text. For backwards compatibility with prior versions of dnspython, they are only emitted in to_text() when requested.

  • Synchronous I/O is a bit more efficient, as we now try the I/O and only use poll() or select() if the I/O would block.

  • The resolver cache classes now offer basic hit and miss statistics, and the LRUCache can also provide hits for every cache key.

  • The resolver has a canonical_name() method.

  • There is now a registration mechanism for EDNS option types.

  • The default EDNS payload size has changed from 1280 to 1232.

  • The SVCB, HTTPS, and SMIMEA RR types are now supported.

  • TSIG has been enhanced with TKEY and GSS-TSIG support. Thanks to Nick Hall for writing this.

  • Zones now can be updated via transactions.

  • A new zone subclass, dns.versioned.Zone is available which has a thread-safe transaction implementation and support for keeping many versions of a zone.

  • The zone file reading code has been adapted to use transactions, and is now a public API.

  • Inbound zone transfer support has been rewritten and is available as dns.query.inbound_xfr() and dns.asyncquery.inbound_xfr(). It uses the transaction mechanism, and fully supports IXFR and AXFR.


  • Python 3.6 or newer is required.

  • The license is now the ISC license.

  • Rdata is now immutable. Use dns.rdata.Rdata.replace() to make a new Rdata based on an existing one.

  • dns.resolver.resolve() has been added, allowing control of whether search lists are used. dns.resolver.query() is retained for backwards compatibility, but deprecated. The default for search list behavior can be set at in the resolver object with the use_search_by_default parameter. The default is False.

  • DNS-over-TLS is supported with dns.query.tls().

  • DNS-over-HTTPS is supported with dns.query.https(), and the resolver will use DNS-over-HTTPS for a nameserver which is an HTTPS URL.

  • Basic query and resolver support for the Trio, Curio, and asyncio asynchronous I/O libraries has been added in dns.asyncquery and dns.asyncresolver. This API should be viewed as experimental as asynchronous I/O support in dnspython is still evolving.

  • TSIG now defaults to using SHA-256.

  • Basic type info has been added to some functions. Future releases will have comprehensive type info.

  • from_text() functions now have a relativize_to parameter.

  • python-cryptography is now used for DNSSEC.

  • Ed25519 and Ed448 signatures are now supported.

  • A helper for NSEC3 generating hashes has been added.

  • SHA384 DS records are supported.

  • Rdatasets and RRsets are much faster.

  • dns.resolver.resolve_address() has been added, allowing easy address-to-name lookups.

  • dns.reversename functions now allow an alternate origin to be specified.

  • The repr form of Rdatasets and RRsets now includes the rdata.

  • A number of standard resolv.conf options are now parsed.

  • The nameserver and port used to get a response are now part of the resolver’s Answer object.

  • The NINFO record is supported.

  • The dns.hash module has been removed; just use Python’s native hashlib module.

  • Rounding is done in the standard python 3 fashion; dnspython 1.x rounded in the python 2 style on both python 2 and 3.

  • The resolver will now do negative caching if a cache has been configured.

  • TSIG and OPT now have rdata types.

  • The class for query messages is now QueryMessage. Class Message is now a base class, and is also used for messages for which we don’t have a better class. Update messages are now class UpdateMessage, though class Update is retained for compatibility.

  • Support for Windows 95, 98, and ME has been removed.