DNS A record monitoring
DoubleCheck looks up your host name and alerts you when it stops resolving or points to an IP address other than the one you expect.
The problem
DNS changes are made in a registrar or DNS panel, often by someone else: a colleague, an agency, a provider. One wrong record and mail, the website or a VPN points to the wrong place.
An expired domain or a hijacked DNS account shows up the same way: the name suddenly resolves somewhere else.
Why it matters
When DNS is wrong, everything behind it is unreachable, even when every server is fine. It is also one of the harder causes to spot, because it looks like an outage elsewhere.
How to check it manually
Look up the A record and compare it with the address you expect:
nslookup -type=A www.example.com
dig +short A www.example.comHow DoubleCheck checks it
DoubleCheck resolves the host name at the interval you choose and compares the result with the IP address you entered. A different address, or no answer, puts the check in error.
- Measures
- A DNS lookup of the host name, comparing the IPv4 address it resolves to with the address you expect.
- Runs
- Every minute by default. You set the interval per check.
- Status
-
- OK when the name resolves to the IP address you expect.
- Error when it resolves to another address, or does not resolve at all.
Frequently asked questions
What happens if my DNS provider is down?
If the name cannot be resolved, the check goes to error, so you notice that too.
Does this work for names with several IP addresses?
Not well. The check compares a single address, so a name that rotates between several addresses (round robin or a CDN) can give false alarms. Use it for names that should always point to one address.
Does it check other record types, like MX or TXT?
Not yet. This check covers A records (IPv4).
Start monitoring with DoubleCheck
Alerts by email, SMS, Slack, Microsoft Teams or Discord. You pay per check run: cost management in the app shows what every check costs, and a longer interval lowers it.