DNS Caching tweaks

When you surf the web, Windows stores recently visited addresses in a DNS cache. The cache is accessed before a request is sent out over the net when a web page address is requested. If the address is found in the DNS cache, it saves time by eliminating the need to request and IP address from a DNS server over the net.

There is a stack of IP addresses in the DNS cache that constantly gets bumped down as IP requests are made. Sort of like a waiting list. This tweak will increase the size of the DNS cache, thus greatly increasing the speed at which web pages are accessed, especially if you regularly check certain web pages.

Open up regedit and go to: HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/Dnscache/Parametersand create/modify these DWORD values: “CacheHashTableBucketSize” set with the value of 1; “CacheHashTableSize” set with the value of 180; “MaxCacheEntryTtlLimit” set with the value of ff00; and “MaxSOACacheEntryTtlLimit” set with the value of 12d.

The second part of DNS caching involves the caching of unsuccessful results. Namely, a valid URL that is temporary offline or cannot be accessed for some reason. As long as that entry remains in the cache and even if the URL goes live again, because Windows refers to the DNS cache first, it will only see the unsuccessful connection and continue to refer to it until it is bumped from the cache. Sounds bad, but there is a way to avoid this with a registry fix that prevents unsuccessful DNS lookups from being cached.

Open regedit and go to HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/Dnscache/Parameters. Create/modify the following DWORD values: “NegativeCacheTime” set with the value of 0; “NetFailureCacheTime” set with the value of 0; and “NegativeSOACacheTime” set with the value of 0. Close regedit and reboot.