I have been trying to make heads or tails on this issue and get more confused about the topic the further I search for it. I am in the process of migrating an old (Windows Server 2003-based) data center for a small company with the main domain, adapteq.com, and two sub-domains, csg and zimbra. Normally, I would log into the firewall and router to see the port forwarding setups and such, but currently do not have access to them to see how it is configured yet, but, having never dealt with configuring/changing sub domains in the past, I am needing to make sure I have the proper information I need. Since we are completely scrapping and replacing the old Windows server data center in favor of Linux across the board, I am having some trouble deciphering how the whole sub domain/port forwarding--if it is still necessary--is configured to handle this. The domains I have personally setup from scratch were all simply a web server and several other servers which listened on different ports on the same machine/FQDN to delineate where the traffic was directed. I configured port forwarding in my router and all is right with the world. Handling sub domains which are on physically separate servers with the same port number--but different internal IP addresses. Here is my setup: Single, static public IP address router which is connected to a Cisco firewall which separates traffic into three subnets: 192.168.10.x (Internal LAN), 192.168.11.x (DMZ), and 172.16.10.x VOIP. The domain, adapteq.com is registered and has the DNS servers configured with the registrar and pointing to our internal servers. Creating subdomain ovd.adapteq.com with internal server address 1.1.1.1 (only used as example) Creating subdomain zimbra.adapteq.com with internal server address 1.1.1.2 (only used as example) Company website is www.adapteq.com with internal server address 1.1.1.3 (only used as example) All servers/sub-domain sites are on the same internal lan (192.168.10.x) and behind the same Cisco ASA firewall and router with public IP. All servers run Ubuntu 14.04.02 server. DNS handled through Bind9 and servers registered with domain name registrar pointer. Here is what I understand at this point: Domain name, adapteq.com, registered with my public IP address and internal DNS servers internal FQDN at the registrar. For company website, www.adapteq.com is configured to the public IP of our router or ASA (I think this is handles NAT, not sure yet) which is configured to forward port 80 to the www.adapteq.com web server on the internal LAN. I understand that for the sub domains that the DNS servers are queried by the domain service to see where in the internal lan these servers are located. Is there any sort of port forwarding or configuration I need to do beyond having the A records for these sub-domains? I would assume it is the same with regard to the MX records being queried for mail transport for the domain? Thank you in advance for helping me understand this. Scott
