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Security Fundamentals & Crypto · Foundational

Screened Subnet

Network segment, formerly called a DMZ, that hosts public-facing services between the internet and the internal network.

Definition

A screened subnet isolates internet-accessible servers such as web, mail relay, and DNS so that their compromise does not give direct access to internal systems. It is typically built with one three-legged firewall or two firewalls in series. CompTIA now uses 'screened subnet' instead of 'DMZ'.

Example

A public web server sits in the screened subnet and can reach only one internal database port.

Exam tip

Security+ uses 'screened subnet' for DMZ; never place internal databases directly in it.

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