Monitoring

    DNS A record change check

    Lemwatch hashes your A records every hour and alerts when the IP list changes — a fast signal for hijacks, misdeploys, or accidental DNS edits.

    Part of DNS monitoring — the full answer, the facts and the alternatives in one place.

    Updated 2026-07-10
    2 min read
    dns
    a-record
    change-detection

    Quick answer#

    Lemwatch resolves your domain's A records hourly, hashes the sorted IP list, and alerts when the hash changes vs the previous cycle.

    What it checks#

  1. All IPv4 A records for the apex and www
  2. Sorted-set hash so record order doesn't cause false positives
  3. Detects additions, removals, and swaps
  4. Cross-checked against 3 public resolvers to filter local anycast noise

    5. Where to find it in Lemwatch#

    Site details → Health → DNS tab. Change events also surface in Activity Log with a "DNS change" pill.

    How to respond#

  5. Open the DNS tab to see old vs new IPs side-by-side.
  6. Confirm the change matches a planned deploy or DNS migration.
  7. If unplanned, check your registrar audit log for unauthorised edits.
  8. Add the new IPs to your CDN allowlist if you use origin protection.
  9. Acknowledge the alert to silence follow-ups for that IP set.

    10. FAQ#

    Will this alert on healthy round-robin rotations?#

    No — the sorted-set hash treats [1.1.1.1, 2.2.2.2] and [2.2.2.2, 1.1.1.1] as identical.

    How fast is the alert?#

    Within one hourly cycle. Pro plans can drop this to 15 min.

    Related#

  10. DNS diagnostics
  11. DNS CNAME change check
  12. DNS NS record check
    13. Was this article helpful?

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