SRV, which is an abbreviation for Service, is a DNS record, which allows you to employ a domain for a certain service different from an Internet site. By creating a few SRV records, you will be able to use the domain address with different companies and point it to several servers at a time, every single server managing a different service. You'll be able to specify the port number for the connection to every machine, so there will never be any interference. You can even set different priorities and weight for two records that are employed for the same service, but point to different servers for redundancy or load balancing. By having an SRV record you can use your domain or a subdomain under it for a Voice-Over-IP server, for example, and have the actual software running on a number of machines with different companies. Which one a customer of yours is going to use depends on the priority and weight values which you have set.