SRV, which is an abbreviation for Service, is a DNS record, which permits you to use a domain for a particular service different from a site. By creating a couple of SRV records, you’re able to use the domain name with different providers and point it to many 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 can even set individual priorities and weight for two records which are used for the exact same service, but forward to different servers for redundancy or load balancing. With an SRV record you can employ your domain address or a subdomain under it for a Voice-Over-IP server, for instance, and have the actual software running on several machines with different companies. Which one a client of yours will use will depend on the priority and weight values you have set.