SRV, which is an abbreviation for Service, is a DNS record, which enables you to employ a domain for a particular service different from a website. By setting up a couple of SRV records, you can use the domain address with different companies and point it to a number of servers simultaneously, each server managing a separate service. You could specify the port number for the connection to each machine, so there will not be any interference. You could also set different priorities and weight for 2 records that are employed for the same service, but point to different servers for redundancy or load balancing. Using an SRV record you can use your domain name or a subdomain under it for a Voice-Over-IP server, for example, and have the actual software running on several machines with different companies. Which one a client of yours will use depends on the priority and weight values you have set.