SRV, which is an abbreviation for Service, is a DNS record, which allows you to employ a domain name for a certain service different from a website. By setting up a few SRV records, you’ll be able to use the domain name with different companies and direct it to many servers at the same time, each and every server handling a different service. You are 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. By having an SRV record you can use your domain or a subdomain under it for a Voice-Over-IP server, for example, and have the specific software running on several machines with different companies. Which one a client of yours will use is determined by the priority and weight values you have set.