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Systems & Data Center · Foundational

/etc/hosts

A local Linux file mapping hostnames to IP addresses, checked before or instead of DNS according to nsswitch.conf.

Definition

Entries take the form IP canonical_name aliases. The lookup order is set by the hosts line in /etc/nsswitch.conf, usually files then dns.

Example

10.0.0.50 db01.corp.local db01 lets the server resolve db01 without DNS.

Exam tip

Stale /etc/hosts entries override DNS and are a classic cause of name resolution problems.

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