DNS flushing

[bigjim999]

Hie I have been getting problems with my internet connection because of DNS errors. I have tried to clear DNS cache using command prompt but am getting message saying dns flushing unsuccessful. I could use some suggestions as to why this is failing, oh! am typing the right command ipconfig/flushdns

from

bigjim999

[Will.Spencer]

What are the exact error messages you are receiving, both when DNS fails and when flushing the DNS fails?

[John]

Firstly, you are using the correct command to flush the DNS cache.

Without any more specifics it is difficult to pinpoint the exact cause of the failure, but there are a number of possible solutions to the problem using just the symptoms outlined.

The main problem with DNS cache is that both positive and negative entries are stored. That is, both successful DNS lookups and failed DNS lookups are stored in cache. Although this generally works well when things are running smoothly, if a website or network device becomes unavailable unexpectedly, it can be a while before you are able to access it again, even if it is present on the network.

A reboot may aid this, though there are no guarantees. I cannot provide anything more specific than this without a little more information about the error message and operating system.

There is a neat trick in Windows XP that ensures that no negative entries are stored, so your machine will attempt to access a failed page or device properly.

You need to add a DWORD to the registry key located at:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet
\Services\Dnscache\Parameters

The DWORD to add is MaxNegativeCacheTtl and its value is 0.

This will ensure that no negative entries are kept and may help prevent you having some DNS problems in the future.

Get back to us with a little more information on what you are trying to access and the exact error message and I may be able to be a little more specific.