RESCAP
The rescap Resolution protocol is a general client-server resolution protocol that translates resource identifiers to a list of attributes. A rescap client can ask a rescap server for the attributes of a particular mail user. Rescap is very lightweight and acts only as a resolution protocol, not a directory service.
Available to all SRX running 12.3X48+
Available to all MX running 20.2R1+
Available to all vSRX running 20.3R1+