Purpose of DNS Client service

[footballking3420]

I have always removed the DNS Client service when using nLite or vLite because it never seemed useful. Am I wrong? Will I get any kind of speed increase by leaving it in and enabling it? I've searched the forums and nobody seems to give a straight answer on whether or not it's actually needed.

[frod]

I have always removed the DNS Client service when using nLite or vLite because it never seemed useful. Am I wrong? Will I get any kind of speed increase by leaving it in and enabling it? I've searched the forums and nobody seems to give a straight answer on whether or not it's actually needed.

Every dns query gets cached for a certain amount of time. On a personnal level, your cable/dsl router does the same and you probably won't every notice the difference with it on or off since for every entry the service uses something like 128 bytes of ram and your network limiting factor is probably not the connection between your router and your computer but the connection between your router and your isp.

On large internal networks however, the dns cache service is pretty useful since there could literally be thousands of requests to the main dns server every minute and having the client computers cache that info could save quite a bit of network bandwidth for other uses.

[Tarun]

I have always removed the DNS Client service when using nLite or vLite because it never seemed useful. Am I wrong? Will I get any kind of speed increase by leaving it in and enabling it? I've searched the forums and nobody seems to give a straight answer on whether or not it's actually needed.

Windows contains a client-side Domain Name System (DNS) cache. The client-side DNS caching feature may generate a false impression that DNS "round robin" is not occurring from the DNS server to the Windows client computer. When you use the ping command to search for the same A-record domain name, the client may use the same IP address. This behavior is different from Microsoft operating systems earlier than Windows 2000. These operating systems do not include the client-side DNS caching feature. This article describes how to disable DNS caching.

Note The overall performance of the client computer decreases and the network traffic for DNS queries increases if the DNS resolver cache is deactivated.

The DNS Client service optimizes the performance of DNS name resolution by storing previously resolved names in memory. If the DNS Client service is turned off, the computer can still resolve DNS names by using the network's DNS servers.

When the Windows resolver receives a positive or negative response to a query, it adds that positive or negative response to its cache, and as a result, creates a DNS resource record. The resolver always checks the cache before querying any DNS server. If a DNS resource record is in the cache, the resolver uses the record from the cache instead of querying a server. This behavior expedites queries and decreases network traffic for DNS queries.

You can use the Ipconfig tool to view and to flush the DNS resolver cache. To view the DNS resolver cache, type ipconfig /displaydns at a command prompt. Ipconfig displays the contents of the DNS resolver cache, including the DNS resource records that are preloaded from the Hosts file and any recently queried names that were resolved by the system. After a certain time period, the resolver discards the record from the cache. The time period is specified in the Time to Live (TTL) associated with the DNS resource record. You can also flush the cache manually. After you flush the cache, the computer must query DNS servers again for any DNS resource records previously resolved by the computer. To delete the entries in the DNS resolver cache, type ipconfig /flushdns at a command prompt.

http://support.microsoft.com/kb/318803