SRV, which is an abbreviation for Service, is a DNS record, which enables you to use a domain name for a specific service different from a website. By creating a number of SRV records, you’re able to use the domain address with different companies and point it to several servers at the same time, every single server handling a separate service. You can specify the port number for the connection to each machine, so there won't be any interference. You can even set individual priorities and weight for two records which are used for the exact same service, but forward 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 instance, and have the real software running on various machines with different companies. Which one a customer of yours is going to use is determined by the priority and weight values that you've set.