Connection good, DNS bad!

pts.
Tags:
DNS
Networking
One computer on LAN is unable to connect to Internet sites. LAN connects to Internet through a router, other computers have no problem. Other computers on LAN are acessible through MS Windows Network. I can ping IP's outside the network, but not URL's - "...could not find host..." Obviously can't connect to a URL with browser, attempts to connect with IP (gateway router or external IP) fails: - Opera: "Illegal address" reported. - Netscape: Nothing at all happens. _ IE: Familiar "page not found" page. Disabling Windows Firewall has no impact. I've never run into this behavior, and hope someone here will recognize it! Obviously the laptop isn't getting responses from the DNS Server, but not being able to connect using IP when Ping reports a clean connection has me baffled. Windows XP Home v. 5.1 (SP2) - to my knowledge the connection was fine after the user installed SP2; other computers on LAN are XP Pro SP1, so that's one difference... Gateway is SMC (NAT router); no change to router configuration since laptop connection worked fine. Thanks for your time! -Bob

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Ok – this looks like a fun one (And yes, I do have a strange idea of fun – profesionally speaking).

1) From a Command prompt enter “ipconfig /all” and verify if the DNS server is, in fact, the correct one. Since you said that this is a laptop, it may have been configured manually for outside settings. This can also be verified by use of the nslookup command to see what default DNS server it is set to use.

2) You mentioned that the system could ping outside IP addresses, but when you mentioned URLs, didn’t specify whether or not these were bare DNS names (like www.yahoo.com) which makes use of the resolver (DNS Client) software.

3) Have you checked this system fully for spyware? This should also include whether or not the hosts file has been modified. (C:WINDOWSsystem32driversetchosts on XP).

Let us know what you find – follow up is ALWAYS appreciated.

Bob (The world would be better with more of us, right Bob?)

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  • VietBob
    Thanks for the lspfix tool, I'll keep it on hand. The problem was indeed spyware/malware-related; the HOSTS file contained scores of entries - I cleaned that up and ran Ad-Aware and Spyware Blaster, and all was well! Thanks, Bob, for pointing me right to the problem, and in the first response I received no less! -Bob
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  • Jpagel
    another good tool out there for you techies (if you dont already know) when you you can obtain an IP but can't surf... 'WinSockFix' rebuilds TCP/IP, registry sockets, and i beleive lsp...enjoy! Josh Complete Computer Service, Inc. NW Indiana
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  • Guardian
    Sorry people,i did not have the chance to reply!Thanks for the info on those tools!!I (well practically everyone that currently uses my ISP)was having hell (especially us in the IT Depts)The ISP servers were down.The mirrored ones where not upto date on the user accounts database(i don't how they managed that).Plus they configured the mirrored servers slightly different.For us on win2000 servers (their servers where not using the PPP protocol)for dial-up.Any practically nation wide (all users of the ISP ecoweb) had no access. Newton Playtime Manufacturers P/L Harare,Zimbabwe
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