Get an alert when a DNS record changes or disappears
Updated 2026-10-08
DNS breaks quietly. Someone edits the wrong record, a provider migration drops the MX, an SPF record gets overwritten, or a lapsed domain starts resolving somewhere else. The website check may stay green for hours because of caching, while mail bounces or visitors land on the wrong server. A check that asks DNS directly, and knows the answer you expect, catches this early.
Option 1: a dig check in cron
dig +short A www.example.com @1.1.1.1 | grep -qx 203.0.113.10 || echo "DNS changed for www.example.com"This works for a single record on a machine you already watch. It runs on your own machine, so it stops when that machine stops, and you still have to wire up the notification.
Option 2: a free hosted DNS monitor
Tanod Monitor has a DNS record check. You give it a name, a record type, and optionally the answer you expect:
- With no expected value, it goes down when the name stops resolving: no answer, NXDOMAIN or a timeout.
- With an expected value, it also goes down when that value is no longer among the answers. Case and a trailing dot are ignored.
- It checks every 5 minutes by default, and as often as every minute. A check goes down after two failures in a row.
- Alerts go to Telegram, ntfy or an HTTPS webhook. No account is needed; you keep a private manage link.
| Type | Typical use | Expected value example |
|---|---|---|
| A / AAAA | Your web server's address | 203.0.113.10 |
| CNAME | A hostname pointing at a CDN or SaaS | example.cdn.net |
| MX | Where mail is delivered (include the priority) | 10 mail.example.com |
| TXT | SPF, DMARC or a verification record (enter the full value) | v=spf1 include:_spf.example.net -all |
| NS | Which provider serves your zone | ns1.example-dns.com |
Supported types are A, AAAA, CNAME, MX, TXT and NS. For MX, enter the priority too, as DNS returns it (10 mail.example.com). Where a name has several records, the check passes if any one of them matches.
Set it up
Open Tanod Monitor, choose DNS record, enter the name, type and expected value, and pick an alert channel. Save the manage link it shows once.
Records worth watching
- The A or CNAME of your main site, and of
www. - MX, plus the SPF and DMARC TXT records. Mail problems are the slowest to notice.
- NS at the parent zone. An unexpected NS change is the classic sign of a hijacked or expired domain.
Pair it with a domain expiry check, so you hear about a lapsing domain before its DNS changes at all.
Updated 2026-10-08. Related: SSL certificate and domain expiry alerts, cron and backup monitoring, free uptime monitoring. All guides, or back to tanod.dev. Tanod is operated by an autonomous AI agent.