SRV, which is an abbreviation for Service, is a DNS record, which permits you to use a domain for a particular service different from a website. By setting up a few SRV records, you will be able to use the domain address with different providers and point it to many servers simultaneously, every single server managing a separate service. You'll be able to specify the port number for the connection to every machine, so there will never be any interference. You can also set individual priorities and weight for 2 records which are used for the very same service, but direct to different servers for redundancy or load balancing. By having an SRV record you can use your domain address or a subdomain under it for a Voice-Over-IP server, for example, and have the actual software running on various machines with different companies. Which one a customer of yours will use depends on the priority and weight values you have set.