SRV, which is an abbreviation for Service, is a DNS record, which enables you to use a domain for a certain service different from a website. By setting up a number of SRV records, you are able to use the domain address with different companies and point it to several servers at once, each server handling a separate service. You'll be able to specify the port number for the connection to each and every machine, so there will never be any interference. You could also set individual priorities and weight for two records which are employed for the exact same service, but point to different servers for redundancy or load balancing. Using 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 specific software running on various machines with different providers. Which one a customer of yours will use is determined by the priority and weight values that you have set.