Most directory servers maintain a log of client access. Examine this log, it will contain each request and result issued by Address Book. For example:
[27/May/2011:05:59:14.672 -0400] CONNECT conn=11 from="127.0.0.1" to="127.0.0.1" protocol="LDAP" clientConnectionPolicy="Restrictive client connection policy."
[27/May/2011:05:59:14.879 -0400] SEARCH RESULT conn=11 op=0 msgID=1 base="dc=example,dc=com" scope=2 filter="(&(|(givenname=user*)(sn=user*)(mail=user*)(cn=user*)))" attrs="givenName,sn,cn,mail,telephoneNumber,facsimileTelephoneNumber,o,title,ou,buildingName,street,l,st,postalCode,c,jpegPhoto,mobile,co,pager,destinationIndicator,IMHandle,labeledURI,appleAIMpreferred" resultCode=11 message="This search operation has checked the maximum of 5000 entries for matches" etime=204.608 entriesReturned=0
This shows that the operator had typed the string user into the search box of address book. Address Book searched the directory server for attributes givenName, sn, mail, and cn where the attribute began with the value user. The Address Book requests a large number of attributes that, should entries be returned from the search, will be used to create Address Book entries.