DNS Troubleshooting for Web Teams
DNS incidents often look random because different resolvers cache records for different durations. A domain may work in one network and fail in another until TTL expires or stale data is replaced. Good troubleshooting starts with record-level visibility before making more changes.
First, verify authoritative records (A, AAAA, CNAME, MX, TXT) and compare them with responses from public resolvers. If the authoritative answer is correct but some resolvers disagree, propagation delay is likely. If authoritative answers are wrong, fix zone data first and avoid repeated edits that extend confusion.
Check DNSSEC, CAA, and nameserver delegation when certificate issuance or email delivery fails unexpectedly. Many outages are caused by incomplete migrations where one part of the chain was updated but another was left pointing to old infrastructure.
Capture timestamps, resolver IPs, and returned values during incidents. Structured evidence prevents guesswork and accelerates postmortems, especially when multiple providers or CDNs are involved.
Open related tool: DNS Analysis
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