SRV, which is an abbreviation for Service, is a DNS record, which allows you to employ 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 companies and direct it to many servers at once, every single server managing a different service. You can specify the port number for the connection to every single machine, so there won't be any interference. You could also set individual priorities and weight for two records which are employed for the same service, but forward 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 actual software running on several machines with different providers. Which one a client of yours is going to use depends on the priority and weight values which you have set.