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Date:      Thu, 24 Jun 2004 18:24:28 -0400
From:      Bill Moran <wmoran@potentialtech.com>
To:        "Dave Raven" <dave@raven.za.net>
Cc:        freebsd-questions@freebsd.org
Subject:   Re: Urgent 4.9 networking problems
Message-ID:  <20040624182428.38e2386d.wmoran@potentialtech.com>
In-Reply-To: <00c801c45a35$388b0d20$3200000a@lucy>
References:  <MIEPLLIBMLEEABPDBIEGEEAOGEAA.Barbish3@adelphia.net> <00c801c45a35$388b0d20$3200000a@lucy>

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"Dave Raven" <dave@raven.za.net> wrote:

> I think I can solve the problem with the BIMAP - I'm just interested in
> finding out why it has to wait to resolve the host name when I'm telnetting
> directly to an ip address and I have no nameservers specified? Surely that
> can't be the way it has to be...

Whether or not this happens will be a function of your telnet server _and_
the telnet client.

It's not unusual to do both forward and a reverse lookup in DNS ... the
reasons are mainly 1) to have something human readible in the logs (IP
addresses aren't really human-readible compared to domain names) and
2) to ensure that you're not being tricked by some sort of DNS spoofing.

While it's probably possible to disable DNS completely, that would be
rather like disabling the turn signals on your car.  It defeats a lot
of what the rules of the highway were designed for.  Much like you
don't understand why you have to use DNS, I can't understand why you're
rebelling against it so much.  Are you saying that there are _no_ DNS
servers on this network for you to plug into?

If you insist on not using any DNS, I can all but guarantee that you
will have weird timeouts to track down for the rest of eternety on this
network.  Most IP programs rely on DNS to some degree.  Some of them
will be able to be configured to skip DNS checks, and some will not,
or will be difficult to convince to ignore DNS.

I temporarily removed /etc/resolv.conf on my desktop machine, and it
caused DNS queries to fail instantly when I tried to use ping.  I
can't say that all programs will react that way, but based on that,
it doesn't seem like FreeBSD's telnet would be timing out on DNS
lookups.

-- 
Bill Moran
Potential Technologies
http://www.potentialtech.com



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