What information will the
ixfr commands in DIG provide to an attacker?
AXFR is the traditional way of zone transferring - you just completely copy the dns records from one zone to the other - an attacker will have a complete list of resources in the organizations and if you save some more information on those servers on your nameserver it will be included
IXFR on the other hand helps sysadmins in replicating an already given zone that was doing a complete AXFR in the past and need to be updated to the latest record revision on the nameserver, without the hassle and band-choking of a complete copy of records. in IXFR you can select the revision that you have and the server will provide you with the updated data since your revision, to an attacker is the same as before - just less information.
She wants to download the zone and discover the list of the machines with ip numbers she can access. This way, I just download the zone, and all the server names and it's ip numbers are revealed, so I look upon systems to which I can have access and I can try my login / password.
Easy way to accomplish this: