HP Multi-Site Traffic Director sa9200 User Manual
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C H A P T E R 4
HP Multi-Site Traffic Director Server Appliance SA9200 User Guide
48
HP SA9200/config/dns/zones/div2.mstd-ex.com#
create-authority ns1.mstd-ex.com ip 10.1.1.1
Authority record ns1.mstd-ex.com created
HP SA9200/config/dns/zones/div2.mstd-ex.com#
create-authority ns2.mstd-ex.com ip 10.1.2.1
Authority record ns2.mstd-ex.com created
HP SA9200/config/dns/zones/div2.mstd-ex.com#
create-authority ns3.mstd-ex.com ip 10.1.3.1
Authority record ns3mstd-ex.com created
HP SA9200/config/dns/zones/div2.mstd-ex.com#
create-authority ns4.mstd-ex.com ip 10.1.3.2
Authority record ns4.mstd-ex.com created
HP SA9200/config/dns/zones/div2.mstd-ex.com#
create authority ns5.mstd-ex.com ip 10.1.4.1
Authority record ns5.mstd-ex.com created
Step 4. Add hosts for the first zone and map their services.
A limitation of DNS is there is no built-in way of conveying exactly
what service the client actually needs. A request for www.mstd-
ex.com could easily be for either HTTP or HTTPS service. A major
feature of the SA9200 is that it is service aware. It knows about the
actual availability of services and can direct clients to the best site for
that service. The problem lies in that the SA9200 has no idea what
service the client wants unless a one-to-one mapping of service types
to host names is made in the configuration.
In this example scenario, it would be easy to lump both the HTTP and
HTTPS services together in the configuration for the hostname
www.div1.mstd-ex.com. But a problem could occur if one of the
services ever failed at a site; the others are still available. Even though
one service has failed, the other is still available and all that is
returned to the client is the IP address. The subsequent attempts by
the client to use the referred address fails because it is asking for a
service that is unavailable at that site.
The solution requires a little more work in the host Web pages, but
allows full advantage to be taken of the service awareness of the
SA9200. If unique hostnames are used for each service type, this
problem never occurs. Note that if the load balancers are HP Traffic
Directors there is less of an issue with combining HTTP services with
HTTPS services. Most of the traffic ever reaching a server would be
HTTP.