DNS Monitoring

Check that your domain resolves to the records you expect

A DNS monitor resolves a domain and compares the answer with the values you expect. It catches DNS misconfiguration, failed propagation and unexpected record changes (including hijacking). It does not check whether the resolved addresses are reachable; pair it with an HTTP or Port monitor for that.

When to use it

• Confirm a domain resolves to the right IP addresses
• Verify a DNS change has propagated
• Watch MX, TXT or NS records for unexpected changes
• Detect DNS server outages

Create a DNS monitor

1. Enter the domain

   Enter the Domain Name, a public domain such as example.com. Private and internal names, IP addresses in private ranges, and UptimeIO’s own domains are not accepted.

2. Add record checks

   In DNS Configuration, click Add Record. Each row has a Record Type, Expected Values and a Match Mode. UptimeIO looks up the current values and fills them in; click the refresh button on a row to fetch them again, or edit them yourself.

3. Optionally choose a DNS server

   Under Advanced Options, leave DNS Server empty to use the default resolver, or enter a resolver IP address such as 8.8.8.8.

4. Set interval and locations

   In How often we check, choose the Check Interval. The shortest interval depends on your plan: 5 minutes on Free, 1 minute on Pro and Scale. DNS answers change slowly, so every 5 minutes is usually enough. Pro and Scale can choose probe locations; Free uses automatic selection.

Settings

Setting	What it does	Default / options
Monitor Name	Name shown in your dashboard	Generated from the domain, up to 80 characters
Domain Name	Domain to resolve	Required
Record Type	The DNS record to check. Each type can be added once per monitor	A, AAAA, CNAME, MX, TXT, NS
Expected Values	The values the record should have. Values are checked for the right format (for example an IPv4 address for A)	At least one per record
Match Mode	How resolved values are compared with the expected values	Match Any (default) or Match All
DNS Server	Resolver to query	Default resolver. Enter an IP address
Check Interval	Time between checks	1 minute to 24 hours. Plan minimum applies
Domain Expiry Monitoring	Domain expiry warnings. See Domain expiry monitoring	Off

Match modes

Mode	The record passes when
Match All	Every expected value appears in the resolved values.
Match Any	At least one expected value appears in the resolved values.

The monitor succeeds only when all record rows pass. A row also fails when no records of that type exist.

For MX records the comparison uses the mail server hostname only (for example mail.example.com), not the priority.

Example

• Domain Name: example.com
• A Record, Expected Values 93.184.216.34, Match All
• MX Record, Expected Values mail.example.com, Match Any
• DNS Server: 8.8.8.8

Record types

Type	Purpose	Example expected value
A	IPv4 address	93.184.216.34
AAAA	IPv6 address	2606:2800:220:1:248:1893:25c8:1946
CNAME	Alias	target.example.net
MX	Mail server	mail.example.com
TXT	Text records (SPF, verification)	v=spf1 include:_spf.google.com ~all
NS	Nameservers	ns1.example.com

DNS server choice

DNS Server	When to use
Empty	Normal resolution as your users would see it
A public resolver (8.8.8.8, 1.1.1.1)	Consistent results independent of the probe’s resolver
Your authoritative nameserver IP	See changes as soon as you make them

Incidents

When a record check fails, UptimeIO records a DNS failure (for example no records found, or a value mismatch). An incident opens only after several probe locations confirm the failure (see Understanding incidents). Connect an email, Slack or webhook channel so unexpected record changes reach you quickly.

Best practices

• Monitor the records that matter: the apex A/AAAA, www, MX and any critical subdomains.
• If you use GeoDNS, answers differ by location; use Match Any rather than one fixed address.
• Before a planned change, lower the record’s TTL a day ahead so the change propagates faster.

Troubleshooting

No records / NXDOMAIN

The domain or record type does not exist. Check registration and nameserver configuration with dig example.com.

Unexpected values

The records changed, a CDN or load balancer returns different addresses, or (if unauthorized) the domain may have been tampered with. Query your authoritative nameserver directly: dig @ns1.example.com example.com.

Invalid DNS server

DNS Server must be an IP address, not a hostname.

Timeouts

Try a different resolver in DNS Server.

Results differ between locations

Propagation may be in progress, or the domain uses GeoDNS.

Next steps

HTTP Monitoring

Monitor web services and APIs

Notifications

Configure alerts for DNS monitors