I was thinking about a project I'm working on for a client of mine. They're
going to have 2 ISP's piped into their network, and use a router that does
failover. I probably won't even need to do this in my case, but I was just
thinking if setting up dual internet w/ failover becomes more common, this
is a situation that could easily be encountered. Most of my clients that
would ever want internet redundancy probably have their own DNS server
anyways. :) I know some of you guys work for ISP's, and there are even a
couple of CCNP's on here I believe. I consider myself very knowledgeable
about TCP/IP, but probably nothing like what you have to know to get a CCNP
or CCIE. (actually, CCNA/CCNP is probably what I should work on next)
The thing I was thinking about, is if you have 2 ISP's, each one has their
own DNS servers. Let's hypothetically say the ISP's are Cox and AT&T (they
aren't actually, for geographical reasons), and each ISP has 2 DNS servers.
Set Cox as the primary ISP, and if that goes down, it fails over to the
slower AT&T line. If you set the computers behind the firewall to Cox's DNS
servers, when it fails over to AT&T, it will probably lose access to Cox's
DNS servers. So, what would be the "best practices" way to combine the two
sets of DNS servers on a network? Obviously most operating systems will let
you put even more than 2 DNS servers, so you can just list them all, which
is probably fine to do if the router doesn't have its own built in DNS
forwarder. (so you could set the PC's to just use 192.168.1.1 as their DNS,
and the router will route the DNS requests on its own)
But, what order should you do it for best performance and reliability? I'm
thinking one of two orders:
Order #1:
Cox DNS 1
AT&T DNS 1
Cox DNS 2
AT&T DNS 2
Order #2:
Cox DNS 1
Cox DNS 2
AT&T DNS 1
AT&T DNS 2
___________________
Nolug mailing list
nolug@nolug.org
Received on 05/14/11
This archive was generated by hypermail 2.2.0 : 05/14/11 EDT