DNS records & domain policy
Technical guides about dns records & domain policy, written for practical follow-up.
Guides in this topic
5 articlesA website works but its email fails: follow the DNS evidence
Separate website records, mail routing and resolver caches when a domain behaves differently across services.
A DNSSEC change broke resolution. Check the delegation first
Investigate DS, DNSKEY and resolver validation behaviour when a signed domain suddenly becomes unreachable.
Before adding a domain to a rule, inspect the exact hostname
Review Unicode labels, Punycode and URL boundaries so allowlists target the intended hostname.
A certificate renewal meets a CAA policy: prepare the issuer change
Check inherited CAA records, wildcard rules and intended certificate issuers before changing certificate providers.
Lowering a DNS TTL today does not clear yesterday's cache
Plan a cutover using the previous TTL, negative answers and the service overlap needed during propagation.
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