SRV, which is an abbreviation for Service, is a DNS record, which enables you to employ a domain for a certain service different from an Internet site. By setting up a number of SRV records, you can use the domain with different providers and point it to numerous servers at the same time, each server handling a separate service. You'll be able to specify the port number for the connection to every machine, so there will not be any interference. You can even set different priorities and weight for two records that are used for the exact same service, but forward to different servers for redundancy or load balancing. By having 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 specific software running on various machines with different companies. Which one a client of yours will use depends on the priority and weight values that you've set.