Windows 7 / Networking

---

Verifying that a Specific DNS Server Resolves Correctly

One of the most common sources of DNS resolution problems is the caching of an outdated DNS address. Particularly on the Internet, DNS servers might continue to return an outdated IP address several hours after a change has been made to the DNS server containing the record. If some clients are unable to correctly resolve an IP address but other systems resolve it correctly, one or more DNS servers have probably cached the incorrect address. To identify the problematic DNS servers, use Nslookup to manually query each server.

To verify that a specific DNS server is able to resolve a host name to the correct IP address, open a command prompt and run the following command.

nslookup hostname server_name_or_address

Nslookup will query the specified server only, regardless of the DNS servers configured on the client. If a specific server returns an incorrect IP address, that server is the source of the problem. Generally, this problem will resolve itself after the incorrect entry expires in the DNS server's cache. However, you can also resolve the problem by manually clearing the DNS server's cache.