Cable Forum - View Single Post - Loss of DNS? in Leeds 4 times in the last 6 days

Matth · 01-12-2004, 20:28

The DNS should not be changing, though if it's the "slow DNS" problem, repeating the action after a few seconds, by which time the DNS has fetched the required record, should succeed - another alternative is to switch to an outside DNS, or for sites that rarely change address, stick the name/number in the hosts file.

http://www.analogx.com/contents/download/network/fc.htm
If nothing else in your system caches DNS (Windows does, but to a very limited degree), then this may help your performance. The first lookup will still be slow, but it'll slice some delay off so long as it remains in the cache.

The firewall issue is basically the problem that if a firewall does R-DNS every suspicious packet (and some DO), then it creates an additional (number of firewall users active) X (number of junk packets they get) load on the DNS server - if many firewalls are doing this, the load could considerably exceed the normal user load, since DNS is normally used only once at connection initiation, and even if no other cache is present, it should not be required again while browsing the same site - if you look at 100 forum posts, you will not be making 100 DNS requests.

01-12-2004, 20:28	#23
Matth Inactive Join Date: Mar 2004 Services: BB:M, TV:XL, Phone:M, Loyalty Posts: 2,516	Re: Loss of DNS? in Leeds 4 times in the last 6 days The DNS should not be changing, though if it's the "slow DNS" problem, repeating the action after a few seconds, by which time the DNS has fetched the required record, should succeed - another alternative is to switch to an outside DNS, or for sites that rarely change address, stick the name/number in the hosts file. http://www.analogx.com/contents/download/network/fc.htm If nothing else in your system caches DNS (Windows does, but to a very limited degree), then this may help your performance. The first lookup will still be slow, but it'll slice some delay off so long as it remains in the cache. The firewall issue is basically the problem that if a firewall does R-DNS every suspicious packet (and some DO), then it creates an additional (number of firewall users active) X (number of junk packets they get) load on the DNS server - if many firewalls are doing this, the load could considerably exceed the normal user load, since DNS is normally used only once at connection initiation, and even if no other cache is present, it should not be required again while browsing the same site - if you look at 100 forum posts, you will not be making 100 DNS requests.