Mail::DKIM::DNS - performs DNS queries for Mail::DKIM
This is the module that performs DNS queries for Mail::DKIM.
This module has a couple configuration settings that the caller may
want to use to customize the behavior of this module.
This global variable specifies the maximum amount of time (in seconds)
to wait for a single DNS query to complete. The default is 10.
Use this global subroutine to get or replace the instance of
Net::DNS::Resolver that Mail::DKIM uses. If set to undef (the default),
then a brand new default instance of Net::DNS::Resolver will be created
the first time a DNS query is needed.
You will call this subroutine if you want to specify non-default
options to Net::DNS::Resolver, such as different timeouts, or to enable
use of a persistent socket. For example:
# first, construct a custom DNS resolver
my $res = Net::DNS::Resolver->new(
udp_timeout => 3, tcp_timeout => 3, retry => 2,
# then, tell Mail::DKIM to use this resolver
This is a convenience subroutine that will construct an appropriate DNS
resolver that uses EDNS0 (Extension mechanisms for DNS) to support
large DNS replies, and configure Mail::DKIM to use it. (As such, it
should NOT be used in conjunction with the resolver() subroutine
Use of EDNS0 is recommended, since it reduces the need for falling back
to TCP when dealing with large DNS packets. However, it is not enabled
by default because some Internet firewalls which do deep inspection of
packets are not able to process EDNS0-enabled packets. When there is a
firewall on a path to a DNS resolver, the EDNS0 feature should be
specifically tested before enabling.
Jason Long, <firstname.lastname@example.org>
COPYRIGHT AND LICENSE
Copyright (C) 2006-2007, 2012-2013 by Messiah College
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself, either Perl version 5.8.6 or, at
your option, any later version of Perl 5 you may have available.