How to troubleshoot DNS records for a domain
A practical DNS checklist for website hosting, email records, domain verification, nameserver changes, SSL certificates, and reverse DNS.
DNS problems often look like unrelated issues: a website does not open, email goes to spam, SSL validation fails, or a SaaS product says the domain is not verified. The fastest path is to inspect the records that control each part of the setup.
A DNS lookup should answer three questions: where the domain points, who is authoritative for the zone, and whether supporting records such as TXT, MX, CAA, and PTR match the service you are configuring.
Website records: A, AAAA, and CNAME
A and AAAA records point a hostname to IPv4 or IPv6 addresses. CNAME points one hostname to another hostname and is common for CDNs, SaaS products, and subdomains.
If a site opens from one network but not another, check whether old records are still cached and whether both apex and www hostnames are configured.
Email records: MX and TXT
MX records define mail servers. TXT records often carry SPF, DKIM, DMARC, and domain verification values.
When email delivery fails, check MX priority, missing SPF includes, incorrect DKIM selectors, and DMARC policy mistakes.
Authority and certificates: NS, SOA, and CAA
NS records show which nameservers are authoritative. SOA exposes the zone serial and timing values, which helps when checking propagation after a change.
CAA records restrict which certificate authorities can issue certificates. A wrong CAA record can block SSL issuance even when A and CNAME records are correct.
DNS troubleshooting checklist
- Check both apex domain and www or important subdomains.
- Verify A, AAAA, and CNAME records for hosting and CDN setup.
- Verify MX and TXT records for email delivery and domain verification.
- Check NS and SOA after changing DNS providers.
- Remember that propagation and resolver caches can temporarily show different answers.
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