What is Integration Server functional alias?
Where can i get the name of "Integration Server functional alias"?

Navigate through IS Admin page -> settings -> JDBC pools page you can find Functional Alias Definitions

Here you can define your Function Alias Definitions(for each and every function in Integration server or component) you can define a Functional Alias in order to categorize and store the data in Embedded Database pool.

Before defining Functional Aliases you should define Pool Alias definitions for each and every DB which you need for storing your Categorized data and Associate each Pool Alias definition with a Functional Alias.

Also Refer: http://idnxchange.com/webmethods-interview-questions/3-webmethods-Interview-questions/189-how-should-i-organise-connection-pools-.html