Strange dial-up problem in Windows XP.

[shdon]

I was called in to troubleshoot a friend's internet connection. They were unable to connect to their dial-up account. Unfortunately, they are running Windows XP, which doesn't seem to allow some of the things I would try under Windows 9x such as re-installing the dial-up adapter, the TCP/IP protocol, forcing a default gateway. Maybe these functions exist, but I couldn't find them.

Anyway, here's what happens:
- (56K) modem dials in (I tested two modems, one internal, one external, both work)
- username and password are accepted (I tried 3 ISPs, login works for every one of them)
- IP addresses are assigned for the client and for DNS servers
- pinging a DNS server works
- ping [ip address for www.microsoft.com] works
- ping

http://www.microsoft.com

doesn't work (failed to lookup hostname)
- nslookup tells me that the DNS servers "aren't responding"
The DNS servers have the correct addresses (I tried forcing them to known good servers) and I can contact them directly using telnet. Odder still, the dial-up connection indicates no traffic when a DNS lookup is performed.

- adding "

http://www.microsoft.com"

with the appropriate address to the C:\Windows\System32\Drivers\etc\hosts file allows me to do "telnet

http://www.microsoft.com

80" and manually sending an HTTP request. I get the correct response then, but cannot access it using IE.

When I run "ipconfig", it gives me the same values for the client's IP address and for the default gateway, which I think is wrong. Still, I can connect to known IP addresses using telnet. What gives?

I tried unchecking "use default gateway on remote network", but that didn't help at all. Reinstalling Windows (not a clean install, which I will do as a last resort only) has no effect.

Dialling in from my Win98 laptop using the same accounts and phone line works perfectly.

I've consulted with some other people who are as baffled as I am and I'm being severely limited by my lack of knowledge of Windows XP. I think it's a routing problem, but surely that should affect telnet and ping as well? Does anybody have any ideas? I'm close to desparation...

 

[GiaBetiu]

Hi,
As I can see it is a problem with that DNS server. Why are you trying to assign a DNS server address manually? Usually ISPs will provide you also these kind of information. But anyway, what you said, proove that DNS is not functioning.
You said that microsoft site is not working even if you will put an address in hosts. Is normal. There will be solved just one address, one IP. ANd in microsoft site, for sure there are indirections, there is load balancing, or other methods, and then hosts is not good at all.
You can ping a server ( that you say that is DNS). It can be any other server. You are pinging an interface from a machine, not a service ( like DNS).
As about what ipconfig is displaying it is correct. Yo will not have assigned a gateway from the other side.
So, again, try to use automatic assigned settings, or if the provider does not provide them (I cannot believe) then you should set them how your ISP indicates. Gia Betiu
m.betiu@chello.nl
Computer Eng. CNE 4, CNE 5

 

[shdon]

No, it is not a DNS problem, unless both my own DNS server as well as the 6 ISP servers (belonging to 3 ISPs) are all problematic, which they aren't. Otherwise I wouldn't have been able to ping them and access them using my laptop or a direct telnet connection. As I said: the DNS entries are correct (I tried forcing it to my own DNS server to see if that would work, but it didn't change a thing). Nslookup also gives the correct DNS hosts, but lists them as "not responding". I know the server I forced it to is correct (I'm sysadmin on that server) and I know the ISPs provide the correct addresses as well. I can ping each and every one of those addresses, but queries don't reach the DNS servers (there is not even outgoing traffic at the moment of a DNS lookup).

 

[GiaBetiu]

I just want to say that pinging a DNS server does not mean that you are testing the DNS server. You just check if that server machine can be reached, has TCP/IP stack correctly lodaed, and it is in the network.
When you want to check a service, try a telnet to that service and port!
like: telnet <server> <port>

And if you are sure that your DNS service can be reached from your location, then check also the default port for resolving DNS used by client ( should be 53). Gia Betiu
m.betiu@chello.nl
Computer Eng. CNE 4, CNE 5

 

[shdon]

Note in my original post: &quot;I can contact them directly using telnet&quot;. Using telnet, I can connect to them and manually request IP addresses, but nslookup (which lists the correct servers on screen) says it doesn't work. The screen looks something like this:

[tt]
C:\WINDOWS>ping 194.109.192.3
[reply is OK]

C:\WINDOWS>telnet 194.109.192.3 53
[no problem querying manually]

C:\WINDOWS>ipconfig /all
[lists 194.109.192.3 as primary DNS]

C:\WINDOWS>nslookup

http://www.microsoft.com

194.109.192.3 *** Server not responding
[note: the dial-up status window indicates no network traffic]
[/tt]

I am a sysadmin on that particular DNS server and I know for a fact that it is set up correctly. Even if it weren't, I refuse to believe that all 7 DNS servers I tried, belonging to 3 ISPs and one private company are all set up in the exact same incorrect way. Something is gobbling up the DNS requests (and other stuff as well) before it even gets to the modem for transport.

 

[GiaBetiu]

Sorry, I didn't understand what you said. For sure you are a good professional.
I can say just that into the client, something (??? ) set the port to a different value than 53. Gia Betiu
m.betiu@chello.nl
Computer Eng. CNE 4, CNE 5