We often need to circumvent customer/client's DNS or supplement them since FQDN is a very stringent requirement for Microsoft SQL Server Mirroring technology.
One of the tricks we use is to edit the local hosts file C:\Windows\System32\Drivers\Etc\Hosts to yield correct FQDN internally.
At one point I have noticed that no matter what I enter the information there, they are ignored.
Also you may have noticed this when the SQL Server Management Studio takes a long time to come up especially in a closed network where there is actually no "outside" route. As I have posted previously, this is due the fact that SQL Server Management Studio performs Certificate Revocation List (CRL) lookup. We usually add
127.0.0.1 crl.microsoft.com
in our local Hosts file so that CRL lookup will purposely fail in order to get the SSMS to come up quicker.
What Worked for Me:
Quick Test: Try to see in your service controller if "DNS Client Service" that is running. If you turn it off, the system starts to look up names in the local Hosts file.
Next you should look your Windows registry.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
In there you will find the value
UseDomainNameDevolution
If this is set to 1, your Hosts wont' work. Just reset this to zero (0)
For additional information on this, find here: http://technet.microsoft.com/en-us/library/cc766230(WS.10).aspx
