Informatica Lookups can be cached or un-cached (No cache).
And Cached lookup can be either static or dynamic.
A static cache:
It is one which does not modify the cache once it is built and it remains same during the session run.
A dynamic cache
It is refreshed during the session run by inserting or updating the records in cache based on the incoming source data. By default, Informatica cache is static cache.
A lookup cache can also be divided as persistent or non-persistent based on whether Informatica retains the cache even after the completion of session run or deletes it