I had a hostgator shared account before which was hosting my 6 sites with 40 subdomains, everything was ok.
One month ago (Jul,15) I moved to a new VPS with 2 dedicated IPs then I setup 4 name servers on godaddy and updated my domains to point to them.
Well now most of my subdomains point back to the old IP of HG servers. At the first I thought that it's the DNS propagation, but it's impossible to last for one month now!
I got messages from many users around the world that sometimes they get dns errors on my sites. The solution is to run flushdns, but It's not possible to tell all the users to make it, also the error may appear again after couple hours.
I tried to decrease the TTL of my domains and their subs, I added new IP, changed the nameservers again but no hope!
Could anyone here help me to understand this strange issue?