DNS Lookup
A practical reference for teams that need to inspect DNS answers before monitoring a hostname.
Free DNS lookup: inspect A, AAAA, CNAME, and other records for a hostname before you point monitoring at it, so a stale record never keeps a check green on the wrong host.
When to reach for this tool
Reach for this when you need to inspect DNS answers before monitoring a hostname during setup, debugging, or an incident review. A one-off check is useful for diagnosis, but production systems need continuous monitoring once the immediate question is answered.
- Confirm A, AAAA, and CNAME records point where you expect.
- A recent DNS change can silently move traffic to a new target.
- Resolve the name before assuming a green check covers the right host.
DNS record types you will check
A DNS lookup returns different record types, and a few come up constantly when setting up monitoring. Confirming these point where you expect prevents the worst monitoring mistake: a green check on the wrong host.
- A — maps a hostname to an IPv4 address.
- AAAA — maps a hostname to an IPv6 address.
- CNAME — aliases one hostname to another; the target is what actually resolves.
- MX — mail servers for the domain.
- TXT — arbitrary text, used for verification and email policy (SPF, DKIM).
- NS — the authoritative name servers for the domain.
From one-off check to continuous monitor
Use DNS results to confirm the hostname resolves to the targets you expect, then monitor the endpoint those records point at continuously.
- Recreate the same check in Sandglass on an interval so the next change is caught without re-running the lookup.
- Send failures to email, a Slack webhook channel, or a generic webhook owned by whoever fixes the problem.
- Track the result over time instead of treating one manual reading as the final answer.
Why a lookup is not monitoring
Monitoring the wrong address is worse than not monitoring at all. Verify the records resolve where you think before you trust a green check on that name.
Use this tool well
Step 1: Run the check and read the result
Use the output to confirm the current state, and treat anything surprising as a starting point for diagnosis rather than a verdict.
Step 2: Define what healthy means
Write down which results count as healthy, degraded, or failed before you automate anything.
Step 3: Promote it to a continuous monitor
Recreate the same check in Sandglass on an interval so the next change is caught automatically.
Step 4: Route the alert to an owner
Send failures to email, a Slack webhook channel, or a generic webhook owned by whoever will fix them.