SRV, which is an abbreviation for Service, is a DNS record, which allows you to employ 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 with different providers and forward it to many servers at a time, every single server handling a different service. You'll be able to specify the port number for the connection to every single machine, so there won't be any interference. You can also set different priorities and weight for 2 records which are employed for the very same service, but point to different servers for redundancy or load balancing. By having an SRV record you can employ your domain name or a subdomain under it for a Voice-Over-IP server, for example, and have the real software running on several machines with different providers. Which one a customer of yours will use depends on the priority and weight values that you have set.