SRV, which is an abbreviation for Service, is a DNS record, which permits you to use a domain name for a particular service different from a website. By creating a number of SRV records, you are able to use the domain with different providers and point it to a number of servers simultaneously, every single server managing a separate service. You can 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 used for the exact same service, but direct to different servers for redundancy or load balancing. By having an SRV record you can employ your domain address or a subdomain under it for a Voice-Over-IP server, for instance, and have the real software running on several machines with different companies. Which one a customer of yours will use depends on the priority and weight values that you have set.