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Create SRV records to enhance DNS flexibility in Windows 2000 Server

This tip shows you how to use SRV records to move a service to a different host and to designate primary and secondary hosts.

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Service location (SRV) records in DNS offer flexibility for networks that contain multiple servers for a particular service. One example of when SRV records come in handy is when you have multiple HTTP servers.

SRV records let you easily move a service from one host to another. Using SRV records, you can also designate specific hosts as the primary host for a given service and others as the secondary host.

Resolvers that support SRV records submit a request to the DNS server in the subject domain, requesting a specific TCP/IP service, such as HTTP. The DNS server responds with a list of all servers in the domain that have a corresponding SRV record for the specified service. The client can then choose a host based on that list.

To create an SRV record, follow these steps:

  1. Open the DNS console on the server, right-click the location for the new record, and choose Other New Records.
  2. In the Resource Record Type dialog box, choose Service Location, and click Create Record.
  3. Select the predefined service type for the service, and choose either TCP or UDP depending on the requirements of the service.
  4. For the Priority value, specify an integer between 0 and 65535 to allocate a preference order for the target server. A lower value gives the server a lower priority; the client attempts connections starting with higher priority servers first.
  5. For the Weight value, specify an integer between 0 and 65535. When multiple servers have the same priority, the Weight value serves as a secondary priority indicator. DNS returns hosts with a higher weight first to the client. To turn off weighting and improve SRV query response time, use a value of 0.

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