[svlug] AT&T DSL - (DNS server?)

Tin Le tin at le.org
Fri Mar 24 08:16:34 PST 2006

>> > So with SBC's default DNS numbers are you saying that it will
>> > resolve http://homeportal to or ?
>> Yes. Since it is the DHCP server, it will assign itself as your first
>> DNS
>> server.
> ...does that mean that it becomes a caching nameserver for the
> clients behind the CIDR or does it only become a "one-address" DNS
> server in only resolving the one address to itself?

These SOHO routers have limited memory, so it's more of a proxying name
server than caching.  It watches DNS requests, answer the handful of name
records it wants control over, the rest is passed up to the next DNS
server (that you've configured the router to use).

> Hmm, so it will hand out a /etc/resolv.conf to clients that has the
> ipaddr of
> the access point as the first numeric entry?  The DNS info that is
> handed out to client machines can be edited one hopes to bypass
> this.

DHCP servers do not hand out /etc/resolv.conf.  They hand out certain
information, and the clients can create a resolv.conf if they want.
Windoze clients do not create a resolv.conf.

If you are on a *nix box, then yes, you can hand edit the resolv.conf.
But remember that it will change back the next time client reboot.  If
you are using dhclient, you can force your own DNS info in

> I've used my Linksys (BEFW-11s4-v2) for years with no issues and of
> course it allows one to determing what DNS information is to be
> handing out to the new client machines.

Yes, pretty much all SOHO routers behaves similarly.

Tin Le
Tin Le - tin at le.org
Firewall and Security Consulting

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