Normally, DNS lookup results are cached, to lower the stress upon name servers; under normal circumstances, DNS changes are rare, and caching the responses is OK.
However, failed DNS lookups are cached, as well. In many cases, when the failure is temporary (DNS server times out, or there are other transient error states), this could lead to a perfectly valid domain name failing to resolve. There are several means to handle that.
1. Reboot the computer to clear the DNS cache. Not a good solution in many cases.
2. Flush DNS cache by running
ipconfig /flushdns
command. However, this cures the consequences, but does not cure the reason.
3. Update your registry. Run regedit utility (please do not forget to make a backup copy of your registry), navigate to
HKLM\SYSTEM\CurrentControlSet\Services\Dnscache\Parameters
and set the following keys to zero:
NegativeCacheTime
NetFailureCacheTime
NegativeSOACacheTime
That will make the computer to request DNS lookup from the upstream DNS server every time. If significant delays are noticed when making DNS queries, it could mean you are asking for a wrong domain name.
However, failed DNS lookups are cached, as well. In many cases, when the failure is temporary (DNS server times out, or there are other transient error states), this could lead to a perfectly valid domain name failing to resolve. There are several means to handle that.
1. Reboot the computer to clear the DNS cache. Not a good solution in many cases.
2. Flush DNS cache by running
ipconfig /flushdns
command. However, this cures the consequences, but does not cure the reason.
3. Update your registry. Run regedit utility (please do not forget to make a backup copy of your registry), navigate to
HKLM\SYSTEM\CurrentControlSet\Services\Dnscache\Parameters
and set the following keys to zero:
NegativeCacheTime
NetFailureCacheTime
NegativeSOACacheTime
That will make the computer to request DNS lookup from the upstream DNS server every time. If significant delays are noticed when making DNS queries, it could mean you are asking for a wrong domain name.
