Dns

A quick reference for using getent to verify how your Linux system resolves hostnames, short names, and IP addresses through the full NSS chain.

When hostname -f returns a short name instead of a fully qualified domain name, the issue usually traces back to the HOSTNAME variable in /etc/sysconfig/network or a misconfigured /etc/hosts entry. Understanding the difference between the gethostname and gethostbyname system calls makes the fix straightforward.

A host health test flags NTP clock drift when the system clock falls out of sync with its NTP servers. This guide walks through diagnosing and resolving common NTP synchronization failures.