The dns.resolver.Resolver and dns.resolver.Answer Classes

class dns.resolver.Resolver(filename='/etc/resolv.conf', configure=True)[source]

DNS stub resolver.

filename, a str or file object, specifying a file in standard /etc/resolv.conf format. This parameter is meaningful only when configure is true and the platform is POSIX.

configure, a bool. If True (the default), the resolver instance is configured in the normal fashion for the operating system the resolver is running on. (I.e. by reading a /etc/resolv.conf file on POSIX systems and from the registry on Windows systems.)

domain

A dns.name.Name, the domain of this host.

nameservers

A list of str, each item containing an IPv4 or IPv6 address.

search

A list of dns.name.Name objects. If the query name is a relative name, the resolver will construct absolute query names to try by appending values from the search list.

use_search_by_default

A bool, specifes whether or not resolve() uses the search list configured in the system’s resolver configuration when the search parameter to resolve() is None. The default is False.

port

An int, the default DNS port to send to if not overriden by nameserver_ports. The default value is 53.

nameserver_ports

A dict mapping an IPv4 or IPv6 address str to an int. This specifies the port to use when sending to a nameserver. If a port is not defined for an address, the value of the port attribute will be used.

timeout

A float, the number of seconds to wait for a response from a server.

lifetime

A float, the number of seconds to spend trying to get an answer to the question. If the lifetime expires a dns.exception.Timeout exception will be raised.

cache

An object implementing the caching protocol, e.g. a dns.resolver.Cache or a dns.resolver.LRUCache. The default is None, in which case there is no local caching.

retry_servfail

A bool. Should we retry a nameserver if it says SERVFAIL? The default is False.

keyring

A dict, the TSIG keyring to use. If a keyring is specified but a keyname is not, then the key used will be the first key in the keyring. Note that the order of keys in a dictionary is not defined, so applications should supply a keyname when a keyring is used, unless they know the keyring contains only one key.

keyname

A dns.name.Name or None, the name of the TSIG key to use; defaults to None. The key must be defined in the keyring.

keyalgorithm

A dns.name.Name or str, the TSIG algorithm to use.

edns

An int, the EDNS level to use. Specifying None, False, or -1 means “do not use EDNS”, and in this case the other parameters are ignored. Specifying True is equivalent to specifying 0, i.e. “use EDNS0”.

ednsflags

An int, the EDNS flag values.

payload

An int, is the EDNS sender’s payload field, which is the maximum size of UDP datagram the sender can handle. I.e. how big a response to this message can be.

flags

An int or None, the message flags to use. If None, then the default flags as set by the dns.message.Message constructor will be used.

canonical_name(name)[source]

Determine the canonical name of name.

The canonical name is the name the resolver uses for queries after all CNAME and DNAME renamings have been applied.

name, a dns.name.Name or str, the query name.

This method can raise any exception that resolve() can raise, other than dns.resolver.NoAnswer and dns.resolver.NXDOMAIN.

Returns a dns.name.Name.

query(qname, rdtype=<RdataType.A: 1>, rdclass=<RdataClass.IN: 1>, tcp=False, source=None, raise_on_no_answer=True, source_port=0, lifetime=None)[source]

Query nameservers to find the answer to the question.

This method calls resolve() with search=True, and is provided for backwards compatbility with prior versions of dnspython. See the documentation for the resolve() method for further details.

resolve(qname, rdtype=<RdataType.A: 1>, rdclass=<RdataClass.IN: 1>, tcp=False, source=None, raise_on_no_answer=True, source_port=0, lifetime=None, search=None)[source]

Query nameservers to find the answer to the question.

The qname, rdtype, and rdclass parameters may be objects of the appropriate type, or strings that can be converted into objects of the appropriate type.

qname, a dns.name.Name or str, the query name.

rdtype, an int or str, the query type.

rdclass, an int or str, the query class.

tcp, a bool. If True, use TCP to make the query.

source, a str or None. If not None, bind to this IP address when making queries.

raise_on_no_answer, a bool. If True, raise dns.resolver.NoAnswer if there’s no answer to the question.

source_port, an int, the port from which to send the message.

lifetime, a float, how many seconds a query should run
before timing out.

search, a bool or None, determines whether the search list configured in the system’s resolver configuration are used for relative names, and whether the resolver’s domain may be added to relative names. The default is None, which causes the value of the resolver’s use_search_by_default attribute to be used.

Raises dns.exception.Timeout if no answers could be found in the specified lifetime.

Raises dns.resolver.NXDOMAIN if the query name does not exist.

Raises dns.resolver.YXDOMAIN if the query name is too long after DNAME substitution.

Raises dns.resolver.NoAnswer if raise_on_no_answer is True and the query name exists but has no RRset of the desired type and class.

Raises dns.resolver.NoNameservers if no non-broken nameservers are available to answer the question.

Returns a dns.resolver.Answer instance.

resolve_address(ipaddr, *args, **kwargs)[source]

Use a resolver to run a reverse query for PTR records.

This utilizes the resolve() method to perform a PTR lookup on the specified IP address.

ipaddr, a str, the IPv4 or IPv6 address you want to get the PTR record for.

All other arguments that can be passed to the resolve() function except for rdtype and rdclass are also supported by this function.

class dns.resolver.Answer(qname, rdtype, rdclass, response, nameserver=None, port=None)[source]

DNS stub resolver answer.

Instances of this class bundle up the result of a successful DNS resolution.

For convenience, the answer object implements much of the sequence protocol, forwarding to its rrset attribute. E.g. for a in answer is equivalent to for a in answer.rrset. answer[i] is equivalent to answer.rrset[i], and answer[i:j] is equivalent to answer.rrset[i:j].

Note that CNAMEs or DNAMEs in the response may mean that answer RRset’s name might not be the query name.

qname

A dns.name.Name, the query name.

rdclass

An int, the query class.

rdtype

An int, the query type.

response

A dns.message.Message, the response message.

rrset

A dns.rrset.RRset or None, the answer RRset.

expiration

A float, the time when the answer expires.

canonical_name

A dns.name.Name, the canonical name of the query name, i.e. the owner name of the answer RRset after any CNAME and DNAME chaining.