SRV, which is an abbreviation for Service, is a DNS record, which allows you to employ a domain for a specific service different from a site. By creating a couple of SRV records, you’re able to use the domain with different providers and point it to many servers at a time, every single server managing a different service. You could specify the port number for the connection to every machine, so there will not be any interference. You can even set different priorities and weight for two records which are used for the exact same service, but direct to different servers for redundancy or load balancing. With an SRV record you can employ your domain name or a subdomain under it for a Voice-Over-IP server, for example, and have the real software running on various machines with different providers. Which one a client of yours is going to use depends on the priority and weight values that you've set.