SRV, which is an abbreviation for Service, is a DNS record, which allows you to employ a domain name for a particular service different from a site. By setting up a couple of SRV records, you can use the domain name with different companies and direct it to a number of servers simultaneously, each server handling a separate service. You could specify the port number for the connection to every machine, so there will never be any interference. You can even set individual priorities and weight for two records that are used for the same service, but point to different servers for redundancy or load balancing. Using an SRV record you can employ your domain name or a subdomain under it for a Voice-Over-IP server, for example, and have the actual software running on a number of machines with different providers. Which one a customer of yours is going to use is determined by the priority and weight values which you have set.