SRV, which is an abbreviation for Service, is a DNS record, which permits you to use a domain for a certain service different from a site. By creating a number of SRV records, you are able to use the domain address with different companies and forward it to numerous servers simultaneously, each server managing a separate service. You are able to specify the port number for the connection to every machine, so there will never be any interference. You can even set different priorities and weight for two records that are employed for the very same service, but direct 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 several machines with different companies. Which one a customer of yours is going to use depends on the priority and weight values that you've set.