I have some networking questions about isolating networks and why it's bad to run DHCP and DNS on a router and should be run on a server.
Question 1:
What is the purpose of the WAN interface and how does it separate a local virtual environment from the public internet? And how is it similar to a cable modem?
Question 2:
DNS and DHCP are typically running on a server; why is it not a good idea to run these services on a router?
Best Answer
WAN is a very subjective term. Routers have interfaces. Some types of router interfaces are more likely to be used as or called WAN interfaces. For example, PPP, HDLC, Frame relay, etc. are rarely used internally in a company, and are generally considered WAN protocols. On the other hand, ethernet, token ring, Wi-Fi, etc. are generally used on an internal LAN. Each of those protocols could actually be used on a WAN or a LAN.
In general, a WAN is a network connecting geographically separate locations.
DNS and DHCP are not actually router functions. Many router vendors include such server software in their router software. The problem is that the router versions of the servers are limited compared to a dedicated server, and you may not want to use router resources (RAM and CPU) to do these functions on a busy router. The real point of a router is to route packets as quickly and efficiently as possible, and running servers can interfere with the primary routing function.