December 2002
Intermediate to advanced
1232 pages
56h 38m
English
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Name
-d8.2
Synopsis
The routine dns_getcanonname( ) in
domain.c of the sendmail
source converts a hostname to a fully qualified domain name. This
routine is called only if DNS is used to look up hostnames, as
determined by the ResolverOptions option (ResolverOptions) and the ServiceSwitchFile
option (ServiceSwitchFile). If it is,
dns_getcanonname( ) can be called from three
places: during startup to get the values for $w,
$j, and $m (-d0.4); when a host is looked up via the
$[ and $] canonify operators
(Section 18.7.6); or when a host is looked up using the
host database map (host).
The -d8.2 debugging switch shows the hostname
before it is fully qualified with this call:
dns_getcanonname(host, flag)
If the flag is nonzero, calls to the getmxrr( ) routine (which looks up MX records) are also traced. On entry to that routine, sendmail will print:
getmxrr(host, droplocalhost=bool)
The host is the hostname whose MX records are
being looked up. The bool, if nonzero, means
that all MX records that are less preferred than the local host (as
determined by $=w) will be discarded. If zero,
they will be retained.
The -d8.2 debugging switch also causes
sendmail to show the result of processing the
ResolverOptions option’s settings
(ResolverOptions) while reading the configuration file:
_res.options = hex, HasWildcardMX = 1 or 0
The hex is a hexadecimal representation of the
state structure’s
options variable as described in
<resolv.h>. The value of
HasWildcardMX is determined by its prefix
(+
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.