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Networking Fundamentals · Foundational

Hosts File

A local text file that maps host names to IP addresses and is checked before DNS on most systems.

Definition

The hosts file is at C:\Windows\System32\drivers\etc\hosts on Windows and /etc/hosts on Linux and macOS. Malware sometimes modifies it to redirect traffic, and administrators use it for testing.

Example

Adding 10.1.1.50 intranet.test to the hosts file overrides DNS for that name.

Exam tip

If one PC resolves a name wrongly but others do not, check its hosts file.

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