Sorry, but I can't see why your code isn't getting it all in one run, but as it isn't, here's another suggestion, although this one sort of works in a backwards method, by getting the ip from the dns hash, then searching for it in the iptracker hash, and if found, deletes it. Hopefully this will work to give you the results you're wanting, even if it's not in the same method that you were trying.
I appreciate the suggestion, but the reason that I'm pulling IP's from the item in the iptracker table is to check if there is a dns item match for the IP. If not, remove that IP from the item in the iptracker table and save the resulting data back to the item in the iptracker table. If after removing a non-matching data value from an item in the iptracker table and the resulting data is $null then delete the item from the iptracker table. If there is a match, go to the next IP for the item in the iptracker table.
