DNS monitoring

The records that point people and mail at your systems, watched for drift from the answer you told hostnag to expect.

Included on every plan.

PlansFreeProBusiness

What DNS monitoring catches
What breaks	hostnag
A DNS record driftsexpected answer missing or changed	Yes
Your nameservers or registrar changenameservers, registrar, DNSSEC, certificate issuer, DNS answers, redirect targets	Yes

How it works

01
Add the hostname and record type
A, AAAA, CNAME, MX, TXT or NS. hostnag resolves it the same way any client would.
02
Say what the answer should be
One or more expected values, matched by contains or an exact set; leave it blank to just watch that the record still resolves.
03
Pick a resolver
The runner's own, or a public resolver you name. A private resolver is refused, the same as a private target.
04
A moved answer is a Changed event
The old and new value both land in the alert, from a location and interval that work the same way as uptime monitoring.

[Warning] DNS answer changed for api.example.com
The api.example.com record now answers 198.51.100.7 (was 203.0.113.10), from every location we checked.
DNS
[Critical] https://www.example.com/ is down
Down from 2 of 3 locations (US East, Frankfurt). Last error: unexpected_status: 503.
HTTP
[Recovered] https://www.example.com/ is back up after 1 h 15 min
https://www.example.com/ answered again from every location. It was down for 1 h 15 min.
HTTP

Sample alerts, rendered by the same code that writes your email and Slack messages.

Can I point it at an internal resolver?

No. A private resolver is refused the same way a private target is.

What if I don't set an expected value?

hostnag still watches for the record resolving at all, and reports its value the moment it changes.

Add a host. Hear about it first.