SRV, which is an abbreviation for Service, is a DNS record, which permits you to employ a domain for a specific service different from a site. By creating a couple of SRV records, you can use the domain name with different companies and forward it to a number of servers at a time, each server managing a different service. You are able to specify the port number for the connection to every machine, so there will never be any interference. You can also set individual priorities and weight for two records that are used for the exact same service, but direct to different servers for redundancy or load balancing. By having an SRV record you can use your domain address 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 companies. Which one a client of yours is going to use is determined by the priority and weight values which you have set.