Gateway Servers in Operations Manager

https://technet.microsoft.com/en-us/library/hh212823.aspx

System Center 2012 – Operations Manager requires mutual authentication be performed between agents and management servers prior to the exchange of information between them. To secure the authentication process between the two, the process is encrypted. When the agent and the management server reside in the same Active Directory domain or in Active Directory domains that have established trust relationships, they make use of Kerberos V5 authentication mechanisms provided by Active Directory. When the agents and management servers do not lie within the same trust boundary, other mechanisms must be used to satisfy the secure mutual authentication requirement.