Internet Problems

[Dr Lobster*]

these internet problems may be part of a bigger backbone issue - we're on a leased bt pipe and i've noticed slow/failed dns lookups as well as timeouts (even though the host seems to have been resolved).

plusnet (my home isp) had dns troubles over the weekend and last night was very slow. i also saw a couple of host not found problems, but refreshing the page or trying again after a couple of minutes solved it.

i wonder if there is a new virus or worm doing the rounds at the minute which is tying up dns?

[Andrew Wood]

plusnet (my home isp) had dns troubles over the weekend and last night was very slow

PlusNet are having big probs at the moment: http://portal.plus.net/supportpages.htm ... d=adsldial

There was a complete lack of service yesterday morning with many knock-on effects.

[Neil Jones]

But why do the DNS servers resolve a domain via ping, rather than through the browser on the same computer? Surely the process is the same?

"Tell me where google.com is"
"It's at 64.233.167.99"

Only then the browser would say "go to 64.233.167.99"?

As a general rule, if you ask for google.com, it goes to your ISP DNS server to find the IP address. If it can't find it there, it'll try to go to a DNS server with a bigger "memory" if you like - more numbers. IIRC there's a layer of about three or more DNS servers working upwards in terms of the amount of numbers they store, and then you get to the Master DNS servers, of which there are only about half a dozen across the planet. If there is no DNS record for a website there, the website therefore doesn't exist and is inaccessible.

But having said that, if your ISP DNS server is out, it can't get online anyway to go to a DNS server with a bigger memory because ironically enough, it needs to find a DNS server number of a DNS server. Which it now can't get.

With regards to ping - all ping officially does is get an DNS address for the domain you ping - the web browser tries to download stuff from the place it was sent to but it's not receiving any data that that website exists and just assumes that it doesn't exist. Reasons for this could be copious - stuffed DNS, stuffed backbone, congestion, ISP problems, etc.

It may not have been a DNS issue, as discussed it could be a more serious internet problem outside of NTL or whoever's control.

But having said that, if an ISP uses its own internal proxy server (which Wanadoo and a few other ISPs do) and that goes belly-up then your DNS will work but no webpages come up.

[Dr Lobster*]

and don't forget neil that there is often going to be complex syncronisation issues with dns too - if the master/slave relationship fails this could cause partial and spurious resolutions.

dns can be a real pain sometimes when it goes titsup - even on a native windows network if the service freezes nobody can login within a few minutes - active directory just won't work without it.

[Neil Jones]

and don't forget neil that there is often going to be complex syncronisation issues with dns too - if the master/slave relationship fails this could cause partial and spurious resolutions.

Yes, but that's going far too deep into it for most people, plus I didn't really want to take that road in all honesty.

[Dr Lobster*]

i notice the forum is quiet this evening... is anybody else having timeouts and routing problems when visiting here? i know plusnet fell over earlier today and the web generally was pretty unusable at 5:30 when i got home from work, but it seems to be a bit better now.

[Bail]

I don't think the weather is helping out people in more remote locations either this evening.

[iSon]

If I type in the address manually it produces a "Page Not Found" - but if I follow the TV Forum link it brings me here.

Odd.