SRV, which is an abbreviation for Service, is a DNS record, which allows you to use a domain for a certain service different from a website. By creating a few SRV records, you can use the domain address with different providers and direct it to numerous servers at a time, every single server managing a separate service. You'll be able to specify the port number for the connection to each and every machine, so there will never be any interference. You can even set different priorities and weight for 2 records that are used for the same service, but point 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 instance, and have the real 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 that you've set.