DNS

Use this skill when the user needs help understanding or troubleshooting DNS behavior across records, delegation, caching, and propagation.

Clarify First

• Which domain or subdomain is in scope.
• What behavior is expected versus what is actually happening.
• Which record types matter for the issue.
• Whether the problem is resolution, delegation, verification, email delivery, or traffic routing.
• What changed recently in registrar, nameserver, or record configuration.

Investigation Priorities

• Confirm authority chain before focusing on individual records.
• Distinguish authoritative answers from cached resolver behavior.
• Check the exact record type and hostname involved.
• Consider TTL and propagation before assuming a change failed.
• Separate DNS-layer issues from application, CDN, or TLS issues.

Common Problem Areas

• Wrong nameserver delegation.
• Record collisions such as incompatible CNAME and other records at the same label.
• Confusing root and subdomain behavior.
• Email-related breakage from SPF, DKIM, MX, or DMARC mistakes.
• Expecting instant global consistency after a DNS change.

Good Output

• DNS diagnosis or setup review by layer.
• Likely source of failure: delegation, record data, caching, or non-DNS system.
• Safe next checks to confirm the theory.
• Change-risk notes around propagation and rollback.

Common Mistakes

• Looking only at one resolver and assuming it represents the whole internet.
• Fixing records before confirming nameserver authority is correct.
• Treating CDN or certificate issues as if they were purely DNS issues.
• Overlooking TTL and stale caches during validation.
• Making multiple DNS changes at once and obscuring the real fix.

Boundaries

• Do not claim a DNS change has fully propagated without evidence from the right vantage points.
• Prefer reasoning about authority, records, and resolution paths over pretending to query live DNS unless the user provides results.