Hi Siga,
I see what you mean. You want to find out specific domains that didn't make it to auction. This is very difficult. You would have to create a list of expired domains that are supposed to go to pre-release auction and then compare it to the actual pre-release list. The zone file has only two things: 1. domain names 2. their nameservers. There is no other information. There is no expiry date, status or registrar.
Also notice that all pre-release domains show as renewed in the whois search because they get 45 days free auto renewal by verisign. You can't create a list of domains that have just expired. Pick any pre-release domain from snapnames or namejet and do a whois check. It will show as renewed.
There is one way to get some information. I checked if registrars use a specific nameserver for expired domains and it turns out they do. Here are the biggest snapnames pre-release partner registrars (ordered bigger to smaller according number of domains they send to auction) and the nameservers they use for their pre-release domains:
REGISTER.COM > NS1.EXPIREDDOMAINS.REGISTER.COM
TUCOWSINC > NS1.RENEWYOURNAME.NET
DIRECTI > DNS.PARKPAGE.FOUNDATIONAPI.COM
MELBOURNEIT > DNS1.NAME-SERVICES.COM
MONIKER > NS1.DOMAINSERVICE.COM
I tried to create a list of domains that use these nameservers, so I can compare it to the snapnames list, however our database is not designed to do this at the moment.
It is also possible that registrars keep some domains for themselves. Register.com for instance does extensive research and they set different custom prices for each quality domain they send to snapnames.
You can check my messages in this topic:
http://www.namepros.com/expired-domains/678386-snapnames-are-they-cheaters.html