DNS (Domain Name System) is the address book of the internet. It translates names like example.com into IP addresses, and it carries other records — mail routing, ownership proofs, certificate authorities — that quietly govern how browsers, mail servers, and security tools reach your domain.
Why it matters
Almost every web request begins with a DNS lookup, so misconfigured records translate directly into outages, slow first-byte times, broken email, or failed certificate issuance. Long TTL values delay recovery from a bad change, and missing or wrong records quietly hurt email deliverability, SEO crawling, and the success of CDN and security integrations. Even short, intermittent DNS errors can break logins, block search engines from re-crawling your site, and trigger false alerts in monitoring.
How to check
- Inventory records per zone: A and AAAA for hosts, CNAME for aliases, MX for email, and TXT for SPF, DKIM, and verifications.
- Use
digornslookupto confirm what authoritative nameservers actually return. - Keep TTL values short before planned changes and longer for stable records.
- Enable DNSSEC to protect responses from tampering and cache poisoning.
- Monitor resolution from multiple regions; some failures are only visible to specific resolvers.
- Document who owns each record so changes do not silently break unrelated services.