SRV, which is an abbreviation for Service, is a DNS record, which allows you to use a domain for a specific service different from a website. By setting up a number of SRV records, you can use the domain with different companies and forward it to a number of servers simultaneously, each server handling a different service. You'll be able to specify the port number for the connection to every single machine, so there won't be any interference. You may as well set different priorities and weight for two records which are used for the same service, but direct to different servers for redundancy or load balancing. With an SRV record you can use your domain address 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 customer of yours will use is determined by the priority and weight values which you have set.