Twisted Names is both a domain name server as well as a client resolver
library.

Twisted Names comes with an "out of the box" nameserver which can read most
BIND-syntax zone files as well as a simple Python-based configuration format.
Twisted Names can act as an authoritative server, perform zone transfers from
a master to act as a secondary, act as a caching nameserver, or any combination
of these.

Twisted Names' client resolver library provides functions to query for all
commonly used record types as well as a replacement for the blocking
gethostbyname() function provided by the Python stdlib socket module.