A DNS monitor asks a resolver for one record type — A, AAAA, CNAME, MX or TXT — on one hostname, every check, and tells you the moment that lookup stops returning an answer.
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DNS monitor · checked every 300s
Configuration
Why this is an issue and not downtime
The A record stopped resolving after a registrar change. The origin server is still running — nothing is “down” in the reachability sense — so this is recorded as a failed check, and the alert names the record that vanished.
Each feature earns its place by making the client relationship easier to protect: fewer surprises, clearer proof, and faster explanations when something changes.
Pick the name and pick the record: A or AAAA for where the site points, CNAME for an alias, MX for mail delivery, TXT for SPF and verification strings. Each check asks the resolver for exactly that record, stores the answers it got back, and times the lookup in milliseconds.
A website can answer perfectly over HTTPS while its MX record has been wiped and mail is bouncing, or while a subdomain CNAME has quietly stopped resolving. An HTTP check will never see that. A DNS monitor asks the question directly.
DNS sits on the same screen as SSL expiry and domain expiry for the same host, so one view answers whether the name still resolves, whether the certificate is still valid, and when the domain has to be renewed.
ErrorDetector keeps two questions apart: could we reach this host at all, and did the check you configured pass? On the same run, a DNS monitor also asks whether the hostname answers over HTTPS — that second answer is what decides the wording.
Shown as “Answered”
The resolver returned at least one record of the type you chose. The answers and the lookup time are stored on the check.
Shown as “No A record”
The lookup returned nothing, but the hostname still answers over HTTPS. The site is not down — a record you depend on stopped resolving. The dashboard names the missing record, your channels get a "Check Failed" alert, and your uptime percentage is untouched.
Shown as “Down”
The lookup failed and the hostname did not answer over HTTPS either — nothing resolves for this name any more. That is a reachability failure: it opens an incident and it counts as downtime.
Both states alert through every channel on the monitor. Only Down opens an incident and moves the uptime number, which is what keeps the figure you hand a client honest.
Concrete moments from the feature: setup, the signal that matters, and the client-facing proof that makes maintenance feel easy and valuable.
Record setup · example data
A DNS monitor resolves one record type for one hostname on your plan interval.
Record type
A
Hostname
acmecorp.comA record
acmecorp.com resolves to 203.0.113.42
Record types
A, AAAA, CNAME, MX and TXT — one type per monitor
Interval
Every 60 seconds on Solo and Team, every 30 on Enterprise
Lookup result · example data
Answers are recorded per check. A name that stops resolving at all is a reachability failure.
Lookup time
38 ms
Answer
203.0.113.42MX acmecorp.com
10 mail.acmecorp.com
TXT acmecorp.com
v=spf1 include:_spf.acmecorp.com -all
CNAME legacy.acmecorp.com
NXDOMAIN — nothing answers for this name any more
Same page as the rest · example data
The name resolving is one of four things that can quietly break a client site.
Hostnames watched
18
Need attention
2acmecorp.com
A record answering · certificate valid for 84 days
acme-store.com
A record answering · certificate expires in 12 days
status.acmecorp.com
CNAME points at errordetector.eu · HTTPS valid
Add the signal once, then let alerts, history, and reports build automatically.
Enter the domain or subdomain you want resolved, for example acmecorp.com or mail.acmecorp.com.
Choose A, AAAA, CNAME, MX or TXT. One record type per monitor — add a second monitor for a second record.
The lookup runs on your plan interval. The moment it returns nothing, the monitor flags a failed check and alerts your channels.
It asks a resolver for one record type on one hostname and records what came back, plus how long the lookup took. The check passes when the resolver returns at least one answer. It fails on NXDOMAIN (the name does not exist), when there is no record of the type you chose, when no nameserver answers, or when the query times out.
No. The check stores the answer it received but does not compare it against a value you set, so a record that starts resolving to a different address still passes. What it catches is a record that stops resolving at all — a wiped MX record, a removed CNAME, a name that no longer exists.
A, AAAA, CNAME, MX and TXT. Each monitor watches exactly one record type on one hostname, so watching both the A record and the MX record for a domain uses two monitors.
Yes, up to your plan’s monitor limit. Each hostname-and-record-type pair counts as one monitor. DNS monitors need a paid plan — the Free plan covers HTTP monitors only.
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