290609 DNS Zones Files Expert Needed

Hello, I download the public accessible root DNS Zone files from the central registries. I take a copy of the root zone files daily. I have access to the .com, .net, .org & .info zone files. In the past, I have paid a programmer to make a solution that grepped & diffed out the zone files - line by line & the output was 2 lists. The lists break down to the following: File1.) Domains Removed from the zone file File2.) Domains Added to the zone file That was all fine in the past. I would take the deleted domains & compile a list. Then I would have lists of domains that will expire in 4-5 days. However, now I am finding that by observing the zone files, there are many domains that are being tasted & are dropped from the root zone files. These domains didn't expire - but instead were dropped by the registry under the grace deletion period. I'd liek to hire someone who has experience with the zone files & can provide help in creating lists of domains. Until recently, a friend of mine share the domains from his zone files & they were all available domains. Unfortanetly, I have been unable to produce lists of "available" domains & we use the same zone files. Maybe what I need to do is store the domains & nameserver info & compare that to the zone file. Then if it is deleted, make my domain lists fromt hat of "available" domains?