RADIUS attribute from rfc5090
When a RADIUS client has asked for a nonce, the RADIUS server
MAY send one or more Digest-Domain attributes in its Access-
Challenge packet. The RADIUS client puts them into the quoted,
space-separated list of URIs of the domain directive of a WWW-
Authenticate header. Together with Digest-Realm, the URIs in
the list define the protection space (see ,) for some HTTP-style protocols. This attribute MUST only
be used in Access-Challenge and Accounting-Request packets.
119 for Digest-Domain
This attribute consists of a single URI that defines a
protection space component.