DNS Monitoring

Monitor your DNS records to ensure your domain configuration is correct and detect unauthorized changes or propagation issues.

Overview

DNS monitoring verifies that your domain's DNS records return the expected values. UptimeObserver queries DNS servers at regular intervals and alerts you when:

DNS records don't match expected values
DNS servers fail to respond
Records are missing or deleted
Unexpected changes are detected

This helps you catch DNS misconfigurations, hijacking attempts, and propagation failures before they impact your users.

DNS monitor creation form

Configuration Options

Hostname

Enter the domain or subdomain you want to monitor:

example.com. — Monitor root domain
www.example.com. — Monitor www subdomain
api.example.com. — Monitor API subdomain
mail.example.com. — Monitor mail subdomain

Record Type

Select the type of DNS record to monitor:

Record Type	Description	Common Use
A	IPv4 address	Primary domain/server IP mapping
AAAA	IPv6 address	IPv6-enabled servers
CNAME	Canonical name (alias)	Subdomains pointing to other domains
MX	Mail exchange	Email server configuration
TXT	Text record	SPF, DKIM, domain verification
NS	Name server	DNS delegation
SOA	Start of authority	DNS zone information
SRV	Service record	Service location (e.g., SIP, LDAP)
CAA	Certification Authority Authorization	SSL certificate issuance control

Expected Value

Specify the exact value you expect at least one returned record to have. Matching is case-sensitive; substring/partial matching is not supported. Use a trailing dot for domain-name values such as CNAME, MX, NS, and SOA targets.

Record Type	Example Expected Value
A	`192.0.2.10`
AAAA	`2001:db8:0:0:0:0:0:10`
CNAME	`cdn.example.net.`
MX	`mail.example.com.` (target only, without priority)
TXT	`v=spf1 include:_spf.google.com ~all`
NS	`ns1.example.com.`
SOA	`ns1.example.com.` (primary nameserver only)
CAA	`0 issue letsencrypt.org`
SRV	`10 5 443 service.example.com.` (priority, weight, port, target)

The IP addresses above are reserved documentation examples, not values to expect from a live domain. Replace all examples with your actual DNS values. IPv6 addresses are compared as text using the resolver's expanded form: use the value shown in the check result, not an equivalent compressed spelling.

For TXT records, quoted chunks within one record are joined without a separator before comparison. Enter the complete resulting text, without the display quotes from dig. If several records are returned, one exact match is sufficient; the check does not require the entire record set to match.

Resolver and Timeout

Monitoring queries use UptimeObserver's configured resolver in each region, with a 1-second DNS query timeout. There is no per-monitor DNS-server setting, and changing the general timeout slider does not change this query timeout. The monitored name must be resolvable from our monitoring servers.

Common Use Cases

Monitor Primary Domain IP

Ensure your domain points to the correct server:

Hostname: example.com.
Record Type: A
Expected Value: 192.0.2.10

Monitor CDN Configuration

Verify your subdomain correctly points to your CDN:

Hostname: cdn.example.com.
Record Type: CNAME
Expected Value: d1234.cloudfront.net.

Monitor Email Configuration

Ensure email routing is correct:

Hostname: example.com.
Record Type: MX
Expected Value: aspmx.l.google.com.

Monitor SPF Record

Verify your SPF record for email deliverability:

Hostname: example.com.
Record Type: TXT
Expected Value: v=spf1 include:_spf.google.com ~all

Monitor DKIM Record

Ensure DKIM signing is properly configured:

Hostname: google._domainkey.example.com.
Record Type: TXT
Expected Value: v=DKIM1; k=rsa; p=...

Here ... is a placeholder. Replace the entire expected value with your full DKIM TXT record; an abbreviated key will not match.

Monitor Nameservers

Verify nameserver delegation:

Hostname: example.com.
Record Type: NS
Expected Value: ns1.dnsprovider.com.

Monitor Load Balancer Failover

Detect if a failover IP has been activated:

Hostname: app.example.com.
Record Type: A
Expected Value: 192.0.2.10 (replace with your primary server's IPv4 address)

Why Monitor DNS?

Detect Unauthorized Changes

DNS hijacking and unauthorized changes can redirect your users to malicious sites. Monitoring alerts you immediately when records change.

Verify Propagation

After making DNS changes, monitor to confirm the new records have propagated to public DNS servers.

Prevent Downtime

Misconfigured DNS records can cause complete service outages. Catch configuration errors before they impact users.

Compliance & Security

For compliance requirements, DNS monitoring provides an audit trail and ensures security records (SPF, DKIM, DMARC) remain intact.

Troubleshooting

Record Not Found

Verify the hostname — Ensure the domain/subdomain exists
Check record type — Confirm you're checking the correct record type
Wait for propagation — New records can take up to 48 hours to propagate

Value Mismatch

Check for trailing dots — DNS records may include trailing dots (e.g., example.com.)
Verify exact value — Ensure the expected value matches exactly, including case
Multiple values — One record must match the complete expected value. An MX priority or abbreviated TXT value will not match

DNS Server Timeout

Check public resolution — Confirm your authoritative nameservers respond from outside your network
Check the affected region — Compare failures across monitoring regions and inspect your DNS provider's status
Contact support — Include the hostname, record type, region, and failed check timestamp; the resolver cannot be changed per monitor

TTL Considerations

DNS records have a Time-To-Live (TTL) value that affects how long records are cached. When making DNS changes:

Lower TTL before changes (e.g., 300 seconds)
Wait for old TTL to expire before monitoring new values
Increase TTL after changes are verified

Need Help?

If you need assistance configuring DNS monitoring, reach out using the "Need Help?" button on the bottom right corner or email us at support@uptimeobserver.com.