There are even more oddities buried in some RRTypes. For example, the 'protocol' field in the DNSKEY RRType. Back when DNSSEC was still in development, the conc

There are even more oddities buried in some RRTypes. For example, the 'protocol' field in the DNSKEY RRType. Back when DNSSEC was still in development, the concept of sub-typing was in vogue and it was thought that RRType codes should be jealously guarded. Fast forward a couple of years and everyone realizes that there are plenty of RRType codes to go around and no one really wants to use DNSKEY for other public keys, so the 'protocol' field was basically frozen with '3' being the only value used. A 35 year old protocol has a lot of vestigial bits, but still vital to network operations.