Time To Live is how long (in seconds) resolvers may cache a record before re-querying. Lower TTLs propagate changes faster but increase query volume; higher TTLs cache longer.

A CNAME aliases one name to another, so the resolver follows it to find the address. A label with a CNAME cannot also hold most other record types at the same name.

A Certification Authority Authorization record lists which CAs may issue certificates for the domain, reducing the risk of unauthorized certificate issuance.