SRV, which is an abbreviation for Service, is a DNS record, which allows you to employ a domain name for a specific service different from a site. By setting up a number of SRV records, you can use the domain name with different providers and direct it to many servers at a time, each and every server managing a separate service. You could specify the port number for the connection to each machine, so there will never be any interference. You can even set individual priorities and weight for 2 records which are employed for the very same service, but forward to different servers for redundancy or load balancing. With 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 providers. Which one a client of yours will use is determined by the priority and weight values which you have set.