SRV, which is an abbreviation for Service, is a DNS record, which permits you to employ a domain for a particular service different from a site. By creating a number of SRV records, you can use the domain name with different providers and forward it to a number of servers at the same time, each server handling a separate service. You'll be able to specify the port number for the connection to each and every machine, so there won't be any interference. You may as well set different priorities and weight for 2 records which are used for the exact same service, but forward 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 a number of machines with different providers. Which one a client of yours is going to use is determined by the priority and weight values which you have set.