SRV, which is an abbreviation for Service, is a DNS record, which allows you to use a domain name for a certain service different from a website. By setting up a couple of SRV records, you will be able to use the domain with different providers and point it to many servers at the same time, each and every server handling a different service. You could specify the port number for the connection to each and every machine, so there will never be any interference. You could also set different priorities and weight for two records that are employed for the very same service, but point 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 instance, and have the specific software running on various machines with different companies. Which one a client of yours is going to use will depend on the priority and weight values which you have set.