SRV, which is an abbreviation for Service, is a DNS record, which permits you to employ a domain name for a specific service different from a site. By creating a couple of SRV records, you can use the domain name with different providers and point it to several servers at once, each server managing a separate service. You can specify the port number for the connection to each machine, so there will not be any interference. You could also set individual priorities and weight for 2 records that are used for the very same service, but forward 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 example, and have the real software running on several machines with different providers. Which one a customer of yours is going to use is determined by the priority and weight values that you have set.