SRV, which is an abbreviation for Service, is a DNS record, which allows you to employ a domain name for a specific service different from a site. By creating a number of SRV records, you can use the domain with different providers and direct it to several servers at a time, every single server handling a separate service. You can specify the port number for the connection to every machine, so there will never be any interference. You can also set individual priorities and weight for two records which are employed for the same service, but point to different servers for redundancy or load balancing. With an SRV record you can employ your domain or a subdomain under it for a Voice-Over-IP server, for example, and have the actual software running on various machines with different companies. Which one a customer of yours will use is determined by the priority and weight values that you've set.