Interesting problem...
- From: "Ball, Dan" <DBall@xxxxxxxxxxx>
- To: "[ISAserver.org Discussion List]" <isalist@xxxxxxxxxxxxx>
- Date: Mon, 28 Feb 2005 08:32:59 -0500
I've finally got most of the slowness out of our Internet access,
everyone was convinced it was due to our ISP, but I had suspicions when
our own published webserver was also slow. Based off of past
experiences, I kept looking at DNS as the most likely culprit, and I was
correct.
I have DNS servers installed on all our DCs, and only the PDC has
forwarding addresses in it, as that is the one that is supposed to
resolve all unknown addresses. While troubleshooting this slowness, I
couldn't find anything wrong, as all DNS queries appeared to be passing
through correctly. After awhile, I decided to again do an ISA log
search for DNS queries, but left the PDC off the filter (not sure why I
didn't do this to start with). I found that the second DNS on the local
subnet was attempting to resolve addresses using a whole bunch of
different IPs. After looking a little further, I realized that all of
the addresses it was attempting to reach were the "root hint" sites.
So, it was a simple fix, I just added the other DNS server to the policy
allowing DNS to pass through, and everything started to run slightly
faster. However, this doesn't really explain what exactly is wrong,
there does appears to be some sort of miscommunication between the DNS
servers.
Anyone have any idea where to start looking? I can't see anything
wrong, other than looking at the logs on the ISA server, everything
seems to be working fine.
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