slapd operational attributes

[Frank Hoffsummer <frank.hoffsummer@svt.se>]

Hello,
we are planning to use openldap2 with
back-bdb on linux as the central userdatabase behind a webforum application.

One functional requirement is to keep
track of the following attributes for each user: 
- last login time
- last IP address
- last modification time (of user attributes)

its seems that these requirements would
lead to an implementation where all authentications would also perform
write operations to the database, which is certainly not desirable. 

I now read about some operational attributes
(such as createTimeStamp and modifiersName) that slapd seems to keep track
of. I checked the documentation, the FAQ and the general Web, but found
no satisfying answers to the following questions

- what operational attributes does slapd
keeps track of automatically?
- can these be configured (i.e. new
attributes added)?
- is it common practice to use these
to fullfill requirements like the ones i described above?
- if not, what is common (best) practice?
(not to use LDAP? or go for a hybrid setup?)

thanks a lot for any insight you might
have!
-frank