Platform: W7 Ultimate, 32-bit W7 installed 20 months ago, no problems until last night. Something broke, and now I cannot resolve DNS lookups. Verizon FIOS, another XP machine on same network is fine, so it can't be the router. Network diagnostics finds nothing. I've tried hard-coding a DNS address, nothing. I'm using a wired interface, I've checked the wiring. I can ping the DNS server, but Windows won't use it to resolve addresses. I'm stumped. Any advice gratefully received. Thanks, dpm

Disable all security softwares and try again. Also, disable your firewall. Please use 4.2.2.2 or your ISP DNS server as primary DNS server and try again. If this does not help, post the output of ipconfig /all > ipconfig.txt. This posting is provided "AS IS" with no warranties or guarantees , and confers no rights. Microsoft Student Partner 2010 / 2011 Microsoft Certified Professional Microsoft Certified Systems Administrator: Security Microsoft Certified Systems Engineer: Security Microsoft Certified Technology Specialist: Windows Server 2008 Active Directory, Configuration Microsoft Certified Technology Specialist: Windows Server 2008 Network Infrastructure, Configuration Microsoft Certified Technology Specialist: Windows Server 2008 Applications Infrastructure, Configuration Microsoft Certified Technology Specialist: Windows 7, Configuring Microsoft Certified IT Professional: Enterprise Administrator

Please try to clear DNS cache with the following command lines. ipconfig /flushdns net stop dnscache net start dnscachePlease remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

I tried all suggestions above, no joy. I gave up and restored a previous backup. Problem solved. I can only guess that something got corrupted. Thanks, dpm