Need SQL Server VLAN advice.. is it best practice to have all SQL Servers under 1 VLAN/network zone?
Is it a best practice to have all SQL Servers in 1 or 2 VLANs within your businesses network?


This is enterprise and personal preference. Some enterprises setup areas for specific things, some don't. You might do it to ease certain administration items and others harder, but overall there isn't anything you specifically gain or lose from doing so.


  Also on firewalls between the SQL Servers &amp; application servers - this is not recommended right, As there will be a bottleneck from the firewall?


This comes down to security requirements. Most enterprises have this in place, but again it's entirely dependent upon your requirements. If you have no requirements you may or may not choose to do this based on the security measures you'd like to enforce. Not everyone specifically wants all servers to be able to talk to all other servers on a network.