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 setting up a few SRV records, you can use the domain name with different companies and forward it to several servers at once, each and every server handling a separate service. You could specify the port number for the connection to every machine, so there will never be any interference. You could also set individual priorities and weight for 2 records that are employed for the exact same service, but forward to different servers for redundancy or load balancing. Using an SRV record you can use your domain name 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 customer of yours is going to use will depend on the priority and weight values which you have set.