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Managing DNS with IPCONFIG in Windows 2000 Pro

Most IT pros use the ipconfig command to view TCP/IP settings and renew a DHCP lease. But did you also know that you can use ipconfig to manage DNS settings on a computer? Find out how you can ipconfig to clear and view the resolver cache, and refresh DHCP leases.

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You've probably used the ipconfig command to view TCP/IP settings and renew a DHCP lease. In addition to these tasks, ipconfig can also help you manage DNS settings on a computer.

For example, the DNS resolver cache tracks the results of DNS name resolution queries so that subsequent queries can be resolved from the cache for better performance. However, Windows caches failed DNS lookups as well as successful ones. If a DNS lookup fails because of a network problem (e.g., a DNS server is offline), you must clear the cache to enable the resolution to work after the network problem is resolved. To clear the resolver cache, use this command:

ipconfig /flushdns

On occasion, you might want to view the contents of the resolver cache. For example, you might want to determine how long before a value expires or identify the IP address for a given host name. Use this command to view the resolver cache:

ipconfig /displaydns

Finally, you can use ipconfig to refresh all DHCP leases and re-register the host's DNS names in its target DNS server:

ipconfig /registerdns

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