SRV, which is an abbreviation for Service, is a DNS record, which enables you to use a domain name for a certain service different from a website. By creating a few SRV records, you can use the domain with different companies and direct it to a number of servers at a time, each server managing a separate service. You'll be able to specify the port number for the connection to each and every machine, so there will not be any interference. You may as well set different priorities and weight for two records that are used 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 specific software running on a number of machines with different companies. Which one a client of yours is going to use depends on the priority and weight values you have set.