SRV, which is an abbreviation for Service, is a DNS record, which allows you to use a domain for a specific service different from a website. By creating a few SRV records, you’ll be able to use the domain address with different companies and forward it to a number of servers at once, each server managing a separate service. You can specify the port number for the connection to every machine, so there won't be any interference. You may as well set different priorities and weight for 2 records that are used for the exact same service, but direct to different servers for redundancy or load balancing. Using an SRV record you can employ your domain or a subdomain under it for a Voice-Over-IP server, for instance, and have the actual software running on a number of machines with different providers. Which one a client of yours will use depends on the priority and weight values you have set.