SRV, which is an abbreviation for Service, is a DNS record, which allows you to employ a domain name for a specific service different from an Internet site. By setting up a couple of SRV records, you are able to use the domain name with different companies and forward it to a number of servers at once, each server managing a separate service. You could specify the port number for the connection to every machine, so there will never be any interference. You may as well set individual priorities and weight for 2 records which are employed for the same service, but direct 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 various machines with different providers. Which one a customer of yours is going to use will depend on the priority and weight values you have set.