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 number of SRV records, you are able to use the domain name with different providers and direct it to a number of servers at the same time, every single server handling a separate service. You could specify the port number for the connection to each machine, so there won't be any interference. You could also set individual priorities and weight for 2 records which are employed 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 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 client of yours is going to use is determined by the priority and weight values that you've set.