Glossary
DNS
CNAME record
An alias pointing one name at another. A name with a CNAME may have no other records, which is why a CNAME cannot exist at a zone apex alongside SOA and NS.
Defined in RFC 1034 §3.6.2.
Where this appears
The lessons that use this term, and what each is for.
DKIM PractitionerCNAME delegation, and who holds the keyChoose between publishing a key and delegating the record, and say who can sign either way.DMARC PractitionerDelegating the recordDelegate _dmarc to a processor, and say what you give up by doing it.Domain Security FundamentalsThe records worth knowing, field by fieldRead a zone’s SOA, NS, A, CNAME, MX, TXT and CAA records and say what each asserts.Domain Security FundamentalsDangling recordsExplain how a leftover DNS record hands an attacker a hostname you own.DNS Security PractitionerThree kinds of danglingRank a dangling CNAME, NS and MX by what each one hands an attacker.DNS Security PractitionerRetiring a service safelyDefine a decommission order that cannot leave a record pointing at claimable infrastructure.Domain Security PractitionerThe CNAME from 2024Work a dangling record whose original owner and purpose are both unknown.