SRV, which is an abbreviation for Service, is a DNS record, which permits you to use a domain for a specific service different from an Internet site. By setting up a couple of SRV records, you will be able to use the domain with different companies and forward it to many servers at the same time, each server managing a separate service. You could specify the port number for the connection to each and every machine, so there won't be any interference. You could also set individual priorities and weight for two records that are employed for the same service, but forward to different servers for redundancy or load balancing. By having 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 a number of machines with different companies. Which one a client of yours will use depends on the priority and weight values that you have set.