Tips for troubleshooting DNS Problems

Tips for troubleshooting DNS Problems

• Make sure you have connectivity to the DNS server?

If your client has communication issues to the DNS server then name resolution is not going to work.

To check what DNS is set on a Windows system use this command:

ipconfig /all

Now take the IP listed for the DNS server and see if the client can ping it or communicate with it.

• Are other users or devices having name resolution issues?

You need to determine how big of a problem you have. Is it just one, two or many devices that have name resolution issues?

If it’s just one then you may just have a client issue. If it’s all or many then you may have an issue with the local or upstream DNS server.

• Use NSLookup to test local server

Use NSLookup to verify the local DNS server is working correctly. Use the command to verify DNS records on local servers. If you need examples see the previous section.

• Use DCDiag to check the AD Health

If your having issues internally you will want to check the Health of your Active Directory environment. Since DNS and AD are very tightly integrated a faulty domain controller could be causing your DNS issues. 

• Use NSlookup server to test forwarding DNS Server (UPstream)

If everything is resolving correctly internally but not external you can test the forwarding DNS server with the NSLookup command. This could be your ISP DNS server or the root hint servers. Use NSLookup server option followed by the forwarding DNS server IP to run queries.

• Scan for viruses and spyware

Viruses and spyware can install all kinds of nasty things on computers to redirect traffic to malicious sites. Browser hijacking is very common

• Check the client’s host file

I don’t recommend adding entries to the host file but if it contains incorrect or outdated data, you won’t be able to connect. Viruses can also modify the host file which would redirect you to malicious websites.

• Flush DNS Cache

The client’s cache could be the problem to flush the cache run this command

ipconfig /flushdns