SRV, which is an abbreviation for Service, is a DNS record, which allows you to employ a domain name for a certain service different from a site. By creating a number of SRV records, you are able to use the domain name with different providers and forward it to numerous servers at the same time, every single server handling a different service. You can specify the port number for the connection to each and every machine, so there will not be any interference. You could also set different priorities and weight for 2 records that are used for the very same service, but point to different servers for redundancy or load balancing. Using an SRV record you can use your domain or a subdomain under it for a Voice-Over-IP server, for example, and have the specific software running on several machines with different providers. Which one a customer of yours will use will depend on the priority and weight values you have set.