SRV, which is an abbreviation for Service, is a DNS record, which allows you to use a domain name for a particular service different from a site. By creating a number of SRV records, you can use the domain with different companies and point it to a number of servers at the same time, each server handling a different service. You are able to specify the port number for the connection to every single machine, so there will not be any interference. You may as well set individual priorities and weight for two records which are employed for the exact same service, but forward 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 specific software running on a number of machines with different providers. Which one a client of yours will use is determined by the priority and weight values that you have set.