We started having a problem yesterday that's continuing today, and I'm not sure how to track down the cause.
The issue is that we're getting sporadic-but fairly regular-DNS lookup timeouts that are killing our Internet connectivity. Here's a sample nslookup: > www.nbc.com<http://www.nbc.com> Server: aoc-pet300.taylor.k12.fl.us Address: 10.11.7.13 DNS request timed out. timeout was 2 seconds. Non-authoritative answer: Name: a1669.b.akamai.net Addresses: 77.67.87.123 77.67.87.91 Aliases: www.nbc.com<http://www.nbc.com> www.nbc.com.edgesuite.net<http://www.nbc.com.edgesuite.net> > Notice that the first request timed out. Sometimes I'll get two or three timeouts before the name is resolved, and sometimes the name won't resolve at all without me trying a second time. This is happening regularly enough that it makes web browsing much slower for all of my users. Each AD site on our network has its own DNS server (aoc-pet300 in my site's case), and these servers are configured to forward requests to our ISP's servers. To determine if those servers were the problem, I configured my site's server to forward to Google's public servers (8.8.8.8 and 8.8.4.4) before my ISP's. No change in the results. When I point nslookup directly to my ISP's or Google's DNS servers and do my lookups against that rather than having my local server forward them, I get no timeouts. All of the servers at my individual sites are exhibiting the same problem, although the others are still configured to forward only to my ISP and not Google. Local lookups of IP addresses and host names on my own network (i.e., those that don't have to be forwarded) are popping right up-so it's not as though everything my DNS servers do is slow. It's only the external forwarding that's problematic. Traceroutes and pings to the external DNS servers show no problems. So I'm stumped. What the heck could be going on here? John Hornbuckle MIS Department Taylor County School District www.taylor.k12.fl.us NOTICE: Florida has a broad public records law. Most written communications to or from this entity are public records that will be disclosed to the public and the media upon request. E-mail communications may be subject to public disclosure. ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ ~ <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~
