ms/http_domain is a SAP Parameter attribute which is used to control Use client's domain for redirect requests information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
If the parameter is set to 1, the message server uses the domain name
with which the client logged on to the message server for the REDIRECT
request. If the parameter has the value 0, the domain that the
dispatcher communicated to the message server is used.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.