DHCP client/DNS related problems (XP Pro)

Ever since I installed Windows XP Pro about two months ago I've had a problem with my internet connection. Everything usually works fine for a while after the computer is switched on, but after a certain period of time (usually between 0.5 to 3 hours) the computer loses its ability to resolve new servers that I visit. Ones I've already been to in this session keep working fine but I can't reach new sites.

I've found that restarting the DHCP client (in Services) frequently provides a temporary fix. (though sometimes it takes several restarts to get to the site I wanted) So I'm guessing it's something to do with that. But really, everything I know about networking could be written on the back of an envelope so who knows.

I'm currently on dialup but the same thing happened back when I used to be on a LAN with broadband. Disconnecting from the ISP does not fix anything. Neither does logging off and logging back in. The problem seems to affect all my programs.
I have Zonealarm running, but I don't think that's causing it.

Can anyone help? It's not debilitating but it is very, very annoying.
Thanks

 

On a stand-alone computer, I would be very surprised if DHCP would be the cause of the problem.

Can you do an:

IPCONFIG /ALL > IPCFGBEFORE.TXT

While connected and everything is working, and then when the problem manifests:

IPCONFIG /ALL > IPCFGAFTER.TXT

and post the two resulting text files to this thread. Both commands are run at the command line.

 

Done so. However both files were identical so will only post it once...



-----------------------------------


Windows IP Configuration



Host Name . . . . . . . . . . . . : sjs

Primary Dns Suffix . . . . . . . :

Node Type . . . . . . . . . . . . : Unknown

IP Routing Enabled. . . . . . . . : No

WINS Proxy Enabled. . . . . . . . : No



PPP adapter BT SURFTIME:



Connection-specific DNS Suffix . :

Description . . . . . . . . . . . : WAN (PPP/SLIP) Interface

Physical Address. . . . . . . . . : 00-53-45-00-00-00

Dhcp Enabled. . . . . . . . . . . : No

IP Address. . . . . . . . . . . . : 81.135.109.198

Subnet Mask . . . . . . . . . . . : 255.255.255.255

Default Gateway . . . . . . . . . : 81.135.109.198

DNS Servers . . . . . . . . . . . : 213.1.119.99

213.1.119.100


----------------------------------------------

Thanks for any help

 

Ah! you're on this side of the pond -

I've had problems in the past with BT servers and I wonder if you have the same root problem. Interestingly I am unable to ping your DNS server from here (a plus net connection). I'd suggest that you try manually setting your DNS to use different DNS servers. How about virgin.net's pair:

192.168.4.100 and 192.168.8.100

I can ping them from here. See how that works.

 

Unfortunately it doesn't seem to have liked that at all. Nothing could be found and I can't ping those DNS servers at all.

I'm guessing it's BT being nasty to little ol me.


(note: I tried restarting the DHCP client and pinging again (in case it was my bug again) and got a different error message)

C:\DOCUME~1\ADMINI~1>ping 192.168.4.100

Pinging 192.168.4.100 with 32 bytes of data:

Reply from 172.16.93.29: Destination net unreachable.

No idea what that means or what it's importantance is, if any.

 

Definitely seen that before on a BT network (atually via an ISP who was using BT for their backbone).

The best tool to see what is happening is TRACERT. You use this command line utility to trace the passage of a packet through the network. I'd recommend you try a TRACERT to www.google.co.uk and then to one of the DNS servers listed in you IPCONFIG output when everything is working, and then do the same when things start going wrong.

So:

TRACERT www.google.co.uk

and then

TRACERT 213.1.119.99

If it is doing what I have seen before the TRACERT will terminate at a BT internal address. The root cause the time I saw it was one of BT's dialup routers going flakey. The company's ISDN router where I was troubleshooting the problem, only hit the troublesome dialup router occasionally (they are set up in banks, so you can get a different one each time you dial up), so the fault was intermittent. When the problem manifested the tracert would get routed into a little private BT network rather than being sent out to the internet.

172.16.x.x is in deed a private address space outside you network. I am sure you are seeing the same problem.

It took a lot of persuading to get BT to investigate. It was the TRACERT output that finally got them moving (together with the ISP's tech support) as the output demonstrated exactly which unit was playing up.