A computer, with Windows 7, can't access any website by domain suddenly.
- Whether this computer use a wired link or connect to the WLAN, The fault persists
- IP and DNS obtained automatically, and seems normal (ipconfig /all return the correct info)
- I can visit websites by using HTTP proxy
- The DNS server is available, other computer in my room works properly.
- I can ping myself, the gateway and any other IP, but domains
- I can use nslookup and obtain the correct IP info
- There are some error information in the event log about dns client events explaining the client can not verify the DNS server available
- Windows network diagnosis explain that Windows can't communicate with the device or resource (Primary DNS Server)
I guess the dns client should be blame. I tried to do the following things but the fault persist.
- Reinstall the driver of network adapter
- Reset TCP/IP (netsh int ip
reset) - Reset Winsock (netsh winsock reset)
- Reset LSP
I don't want to reinstall the whole os, what should I do?
Best Answer
Use a wired connection and boot into Safe Mode with Networking (tap F8 on startup for Advanced Boot Options, it will usually be the third option, after Repair Your Computer and Safe Mode).
This is an informative comparison point as Windows starts with only core drivers and services, and no third-party software.
If it works in safe mode with networking, it tells you there is something loading on normal boot that is interfering, which gives you two options.
Run Windows system restore and choose the latest known working date among the restore points (check if the restore point descriptions note anything unusual - anything besides "System scheduled checkpoint" could be informative). I would do this first, as it performs an entire registry rollback, and then go for the more granular option 2 if this fails.
Open msconfig and have a look at what services and programs are starting on a normal boot. In the services tab of msconfig, check "Hide all Microsoft services" at the bottom, then make a note of all remaining services and disable them. In the startup tab of msconfig, make a note of all the checked items and disable them. Reboot to normal mode. If everything works in normal mode after this, you need to go back into msconfig and selectively enable the important things, among these your security package. If it stops working after reenabling something and rebooting, you have found a culprit.
If it does not work in safe mode with networking, do option 1 above.
In my mind the primary suspects for the behavior you are describing would be malware, a hung security package or - possibly - a windows update gone bad. If you get it working, update your security package and do a full scan.