This article was previously published under Q254809
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Every Exchange Server 5.5 site or Exchange 2000 Server Routing Group needs a Routing Information Daemon (RID) master, or routing master. This RID master generates the routing table for the rest of the site (or Routing Group), which replicates to the entire Exchange Server organization. By default the RID master is the first Exchange Server computer in the site. When an Exchange 2000 Server computer joins the site, you can make either an Exchange 2000 Server computer or an Exchange Server 5.5 computer the RID master. This article explains the implications of this choice.
Some existing Exchange Server organizations may "scope" the address space on a connector, which restricts the visibility of this route to the local Routing Group or local server. "Scoping" is an Exchange Server 5.0 and 5.5 concept that Exchange 2000 does not recognize. Therefore, the Exchange 2000-generated Gateway Address Routing Table (GWART) is incorrect for Exchange Server 5.0 and 5.5 computers.
The only time that the RID master should be an Exchange 2000 Server computer in a mixed Exchange 2000 and Exchange Server 5.5 site is if you upgrade an existing Exchange Server 5.5 RID master computer to Exchange 2000, or if you manually set the RID master by using the Exchange Server 5.5 version of the Exchange Server Administrator program.
In the Exchange Server 5.5 version of the Administrator program, you can choose the RID master in the Site Addressing properties on the General tab. The GWART is always replicated to the Active Directory in a mixed site. RID masters monitor the LegacyGwart object.
Until your site topology is closer to the Exchange 2000 routing scheme, the RID master server should be an Exchange Server 5.5 computer. A good rule to follow is that if there are more Exchange Server 5.5 computers and connectors than Exchange 2000 Server computers, the RID master server should be an Exchange Server 5.5 computer. If address spaces are restricted in scope, it is even more important that the RID master server be an Exchange Server 5.5 computer.