While setting up Database mirroring I came across an error which is too common on the web but too much of workaround and solutions.

Therefore I thought to write a blog post for the error. The problem we’re trying to solve is that you try to start database mirroring and you receive this error:

The server network address “‘TCP: //server FQDN Name:5022′” cannot be reached or does not exist

Database mirroring connection error 4 ‘an error occurred while receiving data: ’64(The specified network name is no longer available.)’.’ for ‘TCP: // server FQDN Name.com:5022’.

I assume that you have the following if not check each of the steps defined below.

1. Full Database Backup of the Database which will be used for DB Mirroring.
2. Restored the Backup on the Mirror Server in No Recovery mode.
   
3. Telnet the ENDPOINT (Port No: 5022 or as per requirement): Ports are opened at both the end (Principle and Mirror).

    

4. Check Endpoints have started on Principal and Mirror.
   SELECT * FROM sys.database_mirroring_endpoints
   SELECT name, port FROM sys.tcp_endpoints
5. Try setting up the DB Mirroring.
6. Start the mirroring.
7. Run netstat to see that end points have established a successful connection.