[ale] DNS best practices

[Bob Toxen]

On Fri, Dec 10, 2004 at 10:44:33AM -0500, Cordell, Ron wrote:
> Hi all,

> I was hoping to draw on your expertise to get an idea of some best
> practices for DNS. 

> I'm trying to determine if it is best to have one DNS server, or
> multiple DNS servers for an environment. The environment consists of a
> few hosts in a DMZ, with many hosts behind a firewall (behind the DMZ).
> The hosts behind the firewall are divided up into vLANs, and are in
> several subdomains. Does it make sense to put a single DNS server in the
> DMZ, and use that, or would you recommend putting the server elsewhere?
> If machine resources are scarce, I don't want to have to create a lot of
> DNS servers.

> I appreciate any suggestions.
If your firewall is good, i.e., someone on the Internet cannot spoof
packets to appear to come from your DNS server, then one DNS server
(or a pair for redundancy) in the DMZ should suffice, assuming it is
running on a hardened Linux or UNIX system.

Of course, you'll want to ensure that your internal DNS entries cannot be
obtained by anyone from the Internet.  Of course, properly configuring
a DNS server is non-trivial.  You'll also want to ensure that it's kept
up-to-date w.r.t. security patches.

> -ronc

Bob Toxen
Fly-By-Day Consulting, Inc.
"Your expert in Firewalls, Virus and Spam Filters, VPNs,
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