DNS Resolution Check

Slug

N3ESXJ5Y4G7M

Fetches

0

Size

1111 B · 48 lines

Expires

never

Last fetch

—

Created

2026-09-07 00:35:59.240

Description

Resolve hostnames with getent

#!/usr/bin/env bash
# DNS resolution check
# Read-only: resolves names with getent ahosts (fallback: getent hosts). Default example.com.
# Exit 0 if every name resolves, 1 if getent is missing, 2 if any name fails.
# Hosted on Runny.sh. Review the script page before you run it.

set -u

status=0
note() { printf '%s\n' "$*"; }
bump() {
  case $1 in
    crit) status=2 ;;
    warn) [ "$status" -lt 1 ] && status=1 ;;
  esac
}

if [ "$#" -eq 0 ]; then
  set -- example.com
fi

note "=== DNS resolution ==="
if ! command -v getent >/dev/null 2>&1; then
  note "getent:   not found in PATH"
  note "Result: WARNING"
  exit 1
fi

for name in "$@"; do
  note "Name:     ${name}"
  rows=$(getent ahosts "$name" 2>/dev/null || getent hosts "$name" 2>/dev/null || true)
  if [ -z "${rows}" ]; then
    note "          CRITICAL: no A/AAAA records"
    bump crit
  else
    printf '%s\n' "$rows" | awk '!seen[$1]++ {printf "          %s\n", $0}'
    note "          OK"
  fi
  note ""
done

case $status in
  0) note "Result: HEALTHY" ;;
  1) note "Result: WARNING" ;;
  *) note "Result: CRITICAL" ;;
esac
exit "$status"