SRV, which is an abbreviation for Service, is a DNS record, which allows you to use a domain name for a particular service different from a site. By setting up a couple of SRV records, you’ll be able to use the domain address with different companies and forward it to a number of servers at once, each server handling a different service. You could specify the port number for the connection to every single machine, so there won't be any interference. You could also set different priorities and weight for two records that are employed for the same service, but direct to different servers for redundancy or load balancing. Using an SRV record you can employ your domain address or a subdomain under it for a Voice-Over-IP server, for instance, and have the real software running on a number of machines with different providers. Which one a customer of yours will use will depend on the priority and weight values that you have set.