Check dns

Overview

Performs a DNS lookup and converts a hostname to one or more IP addresses. Only the name servers configured on the machine running this check plugin (for example those in /etc/resolv.conf) will be queried - you can’t query other DNS servers. When no arguments or options are given, the check tries to resolve localhost, and the full range of results for any available protocol is returned.

This command works with both IPv4 and IPv6.

Fact Sheet

Check Plugin Download

https://github.com/Linuxfabrik/monitoring-plugins/tree/main/check-plugins/dns

Check Interval Recommendation

Every 15 minutes

Can be called without parameters

Yes

Compiled for

Linux, Windows

Help

usage: dns [-h] [-V] [--always-ok] [-c CRIT] [-H HOSTNAME] [-p PORT]
           [--type {udp,udp6,tcp,tcp6}] [-w WARN]

Performs a DNS lookup and converts a hostname to one or more IP addresses.
Only the name servers configured on the machine running this check plugin (for
example those visible in `/etc/resolv.conf`) will be queried - you can't query
other DNS servers. This command works with both IPv4 and IPv6.

options:
  -h, --help            show this help message and exit
  -V, --version         show program's version number and exit
  --always-ok           Always returns OK.
  -c CRIT, --critical CRIT
                        Return critical if elapsed time in ms exceeds value.
                        Default: None
  -H HOSTNAME, --hostname HOSTNAME
                        The host or ip address to check. Default: localhost
  -p PORT, --port PORT  The port number. Default: 53
  --type {udp,udp6,tcp,tcp6}
                        Connection type. Can be optionally specified in order
                        to narrow the list of addresses returned.
  -w WARN, --warning WARN
                        Return warning if elapsed time in ms exceeds value.
                        Default: None

Usage Examples

./dns --hostname $(hostname)
./dns --hostname www.example.org --type udp --port 53 --warning 1000 --critical 5000

Output:

Lookup for webserver.linuxfabrik.ch returns 192.168.26.43 (tcp4:53), 192.168.26.43 (udp4:53), 192.168.26.43 (ip4:53)

States

  • WARN on socket errors, address related errors, network timeouts.

  • WARN or CRIT if you provide thresholds for the DNS lookup time duration.

  • Otherwise OK.

Perfdata / Metrics

Name

Type

Description

time

Milliseconds

DNS lookup time

Credits, License