SRV, which is an abbreviation for Service, is a DNS record, which enables you to employ a domain for a certain service different from a website. By setting up a number of SRV records, you will be able to use the domain name with different companies and point it to a number of servers at a time, each and every server handling a different service. You can specify the port number for the connection to each machine, so there will not be any interference. You may as well set individual priorities and weight for two records that are employed for the exact same service, but point to different servers for redundancy or load balancing. Using an SRV record you can use your domain address or a subdomain under it for a Voice-Over-IP server, for example, and have the real software running on various machines with different companies. Which one a client of yours will use is determined by the priority and weight values you have set.