For me the Back-end is testing a system that runs behind
the front-end (GUI Applications). It can be Database
testing, Server Side testing.
Talking about Database testing, it can involve:
-> Data validity testing
-> Data integrity testing
-> Performance related to Databse specially when working
with Views and Indexes.
-> Testing of procedures,functions and triggers.
Server Side testing can involve the servers running on Unix
(Solaris, AIX)/Linux, mainframes systems. The parameter to
be monitered can be:
-> Server logs
-> jvm logs (Is its a Java based application)
-> Checking the Garbage Collector (GC) values and see if
its happening properly or not by tuning its parameters
-> Server downtime
-> Sever response time
-> Checking batch processes in Unix etc..etc..