What is a DMZ in networking?

A DMZ (demilitarised zone) is a separate network segment for servers that must be reachable from the internet, such as a public web server, mail gateway or remote-access gateway, kept apart from the internal network. If one of those exposed servers is compromised, the firewall rules between the DMZ and the internal network limit what the attacker can reach next. The idea is simple: what faces the internet should not sit next to your file server. Watch traffic from the DMZ toward internal systems closely; a DMZ server starting new sessions inward is a strong sign of trouble.

← All 69 questions on What is…? Network and security termsAll topics