HP-UX OSRA for Web Services 2.5 Blueprint and Configuration Guide

NOTE: Setting the TTL value to zero is not recommended because it can, cause problems with
the DNS proxy servers. It is common to set the TTL to a small value, such as five minutes, because
many web clients use DHCP and must react quickly to changes in their IP address allocation.
After changing the TTL value, restart the named server as described in the previous section.
Disable the Java DNS Cache
Java 1.5 does not use the DNS TTL value you set in the zone configuration file. If you run your
web client in a JVM, you must specify your own TTL value.
By default, Java caches DNS addresses indefinitely. To disable DNS caching, start the JVM with
the following properties:
# java -D networkaddress.cache.ttl=0 -D sun.net.inetaddr.ttl=0...
Using DNS Round Robin With Application Servers
If you are using DNS Round Robin to load balance across a cluster of application servers, you
cannot store state information on the application server unless you replicate the state information
to the other servers in the cluster.
Clustering provides your application with application server failover capabilities, but it requires
system and network resources to implement, and may not scale out as servers are added to the
cluster.
Horizontal Scaling of Web and Application Servers 33