Hi Brian, Ok starting with the MRA Expressway pair first.  At a minimum you will need the Expressway-C to include the domain used to discover the edge (via collab-edge DNS SRV) in the Configuration > Domains menu.  The domain(s) will be provided to Expressway-E once the unified communications traversal zone is established and allows the Expressway-E to only allow traffic for the configured domains.  This appears to be exampledomain.com from your post.  If you are using IM&P, you'll want to include the presence domain as well on the Exp-C, and enable IM&P service in the domain config.  Take a look at the following application note that includes a worst case multi-domain scenario, Configuration Example: Mobile and Remote Access through Expressway/VCS in a multi-domain deployment - Cisco B2B DNS SRV records will likely align with exampledomain.com, but you can publish other records if need be. They don't need to be related to Jabber service or presence domains.  And there's no requirement to specify domains used for B2B in the Exp-C Configuration > Domains menu.  Only search rules and CPL rules are usually needed. No DNS SRV records required for Jabber Guest, but you do need to have a domain configured on Exp-C that allows inbound jabber guest traffic for your domain.  And similar to B2B, there's no requirement for the Jabber guest domain to align with Jabber service or presence domains. HTH, Kevin ... View more