From X8.11 of Cisco Expressway, a new concept of load balacing based on priority and weight instead of the round robin for better load balancing and probe is added to prevent the Cisco Expressway-C to sollicit a webbridge when it is down.Assume all the Cisco Meeting servers has different capacity, we can use a special SRV record _cms-web.tls.join.lab.public (note: join.lab.public is the url the remote user will type to use WebRTC based-browser in order to connect to a meeting, using this special SRV record we can configure a high prority for webbridge with high capacity to allow more WebRTC connections to go there from Expressway-C for better load balancing.
If the webbridge servers have the same capacity, for better load load balacing, use the same priority and weight values.A probe is sent periodically by the Cisco Expressway-C to query the DNS server if the ip address of the webbridge is reachable. If not, it marked the webbridge as failed and will no longer sollicit the failed webbridge.
A changes need to be made on the internal DNS server to create a Forward Lookup Zone that matches the Guest Account Client URL (the URL the remote user types in the web browser).See below how to create the SRV records _cms-web.tls and how the WebRTC connection is established.
Demystify and Simplify 