- dns_rdatatype_ismulti() returns true if a given type can have multiple answers: ANY, RRSIG, or SIG. - dns_rdatatype_issig() returns true for a signature: RRSIG or SIG. - dns_rdatatype_isaddr() returns true for an address: A or AAAA. - dns_rdatatype_isalias() returns true for an alias: CNAME or DNAME.