A demilitarized zone (DMZ), or perimeter network, is an internet-exposed network segment that buffers untrusted traffic from internal systems. It contains hardened components rather than application services themselves. section 9.2
Use a DMZ to reduce exposure and control inbound API traffic:
- Channel inbound traffic through an API gateway, reverse proxy, load balancer, or similar internet-facing technology in the DMZ. section 9.2
- Keep services in private subnets without direct internet access, allowing communication across segments only through controlled network bridges and access rules. section 9.2 section 9.5
API infrastructure layout
Place an API gateway and bastion server in the DMZ, route approved inbound requests toward private APIs, and restrict the bastion server to traffic from permitted origins. Keep internal databases and development endpoints out of the internet-facing segment.

