SRV, which is an abbreviation for Service, is a DNS record, which permits you to use a domain name for a specific service different from a site. By setting up a number of SRV records, you will be able to use the domain with different providers and point it to several servers at once, every single server handling a separate service. You'll be able to 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 two records that are used for the same service, but forward to different servers for redundancy or load balancing. Using an SRV record you can employ your domain or a subdomain under it for a Voice-Over-IP server, for example, and have the actual software running on a number of machines with different companies. Which one a customer of yours is going to use is determined by the priority and weight values that you have set.