Accessing servers with DNS aliases

When trying to access a windows server via a DNS alias (e.g. using \\fileserver.company.co.uk that is an alias of \\SERVER12), you will probably get a ‘duplicate name exists on the network’ error. This is because the default behaviour of windows only permits using the proper name of the server (SERVER12 in this case, or a bound IP address). This applies to both CNAMEs and A records in DNS.

You might have aliases set up so that if you ever move a service onto a different server, all you have to do is update the alias.

To enable a windows server to respond to aliases like this, you’ll need to edit the registry. Navigate to:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\lanmanserver\parameters

Then add a new DWORD value, called DisableStrictNameChecking and the the value to 1.

Once this is done, you’ll need to restart the server service, after that you should be able to access the server using the alias name!

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