SRV, which is an abbreviation for Service, is a DNS record, which allows you to employ a domain for a certain service different from a website. By creating a couple of SRV records, you will be able to use the domain name with different companies and point it to numerous servers at the same time, every single server handling a separate service. You can specify the port number for the connection to each machine, so there will never be any interference. You can also set individual priorities and weight for 2 records that are used for the exact same service, but direct to different servers for redundancy or load balancing. With an SRV record you can employ your domain address or a subdomain under it for a Voice-Over-IP server, for instance, and have the specific software running on a number of machines with different companies. Which one a client of yours is going to use will depend on the priority and weight values that you have set.