SRV, which is an abbreviation for Service, is a DNS record, which permits you to use a domain for a certain 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 at a time, each server managing a separate service. You can specify the port number for the connection to each and every machine, so there won't be any interference. You can also set different priorities and weight for 2 records that are employed for the exact same service, but point 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 instance, and have the real software running on various machines with different providers. Which one a customer of yours will use depends on the priority and weight values that you have set.