SRV, which is an abbreviation for Service, is a DNS record, which enables you to use a domain name for a particular service different from a website. By creating a few SRV records, you are able to use the domain with different companies and direct it to a number of servers at the same time, every single server handling a different service. You can specify the port number for the connection to each and every machine, so there will not be any interference. You may as well set individual priorities and weight for two records that are employed for the same service, but point to different servers for redundancy or load balancing. By having 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 client of yours will use will depend on the priority and weight values which you have set.