SRV, which is an abbreviation for Service, is a DNS record, which permits you to use a domain name for a particular service different from a site. By creating a number of SRV records, you will be able to use the domain name with different companies and forward it to numerous servers at once, each and every server handling a different service. You can specify the port number for the connection to every single machine, so there will never be any interference. You could also 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 address 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 client of yours is going to use depends on the priority and weight values that you have set.