Which DNS record is commonly used to publish DKIM public keys?

Which DNS record is commonly used to publish DKIM public keys?

• A. TXT Record
• B. A Record
• C. MX Record
• D. CNAME Record

Answer: (A)

DKIM public keys are published in DNS, and the standard method is a TXT record. The TXT record holds the actual public key data (and related DKIM parameters) in a text string that mail receivers can fetch and parse to verify a DKIM signature. This record is placed under a name that includes the selector, like selector._domainkey.example.com, so verifiers know which key to use for a given signing domain. Other DNS record types serve different purposes: A records map hostnames to IP addresses, MX records specify mail servers, and CNAME records create aliases. None of these are designed to carry the cryptographic key material in the format DKIM requires, so they aren’t used to publish the DKIM public key.

DKIM public keys are published in DNS, and the standard method is a TXT record. The TXT record holds the actual public key data (and related DKIM parameters) in a text string that mail receivers can fetch and parse to verify a DKIM signature. This record is placed under a name that includes the selector, like selector._domainkey.example.com, so verifiers know which key to use for a given signing domain.

Other DNS record types serve different purposes: A records map hostnames to IP addresses, MX records specify mail servers, and CNAME records create aliases. None of these are designed to carry the cryptographic key material in the format DKIM requires, so they aren’t used to publish the DKIM public key.