SRV, which is an abbreviation for Service, is a DNS record, which enables you to use a domain name for a particular service different from a site. By setting up a few SRV records, you’ll be able to use the domain name with different providers and forward it to several servers simultaneously, each server managing a different service. You are able to specify the port number for the connection to each machine, so there will never be any interference. You may as well set individual priorities and weight for 2 records that are used for the same service, but point to different servers for redundancy or load balancing. Using an SRV record you can employ your domain address or a subdomain under it for a Voice-Over-IP server, for example, and have the specific software running on a number of machines with different companies. Which one a customer of yours will use depends on the priority and weight values that you've set.