We host the DNS for our domain.
Two weeks ago, the developer requested that we setup a new zone 'dev.ourdomain.com' and place two host records in it my.dev.ourdomain.com and admin.dev.ourdomain.com.
We added the zone to our DNS and added A records for the host.
Now a week later, some DNS servers like google (8.8.8.8) and gtei (4.2.2.2) will resolve the hosts, but others like OpenDNS (208.67.222.222 ) and ATT Uverse (68.94.156.1) cannot resolve it.
Any Ideas?
I assume you already waited any TTL involved so you are sure there are no 'old' data in caches around the world.
You should check the whole resolving chain from the TLD down to your zones for any problem. Eg., start at .com and ask its authoritative name servers for the list of NSes of your domain. Then go ask each one of them for NSes of your sub-domain, and go ask them too for any data that should be published.
Chances are some dns isn't publishing the whole data, then you actually have a 'replication issue' as said in the title. Or maybe you miss some data somewhere (SOA, NS, or the like...)
If a standard resolver (I'd use dig, for example) can resolve your hostnames, then the problem could lie at the other end.
You said you added a zone to your server, why? Is the server that handles dev.yourdomain.com not the same that handles yourdomain.com? You shouldn't have to create a separate zone file if the same hosts are managing the parents. You don't mention what server, so I'm going to assume bind, but most dns services will support doing something like this:
These entries both appear in the main zone file. If however you are planning on hosting DNS for the dev.yourdomain.com subdomain somewhere else, then you need something a little more complicated. Setup your zone file as you have, then add references from the parent servers:
As for the actual issue of some hosts not resolving, have you run a trace? Is it all the time? Are they querying the same NS hosts? Have you validated the configurations on multiple servers, if you're running multiples?
Check which name servers are listed in WHOIS for the domain, then query each of those servers for the NS records for the domain and make sure they all list the same name servers. If they don't, then you need to get them fixed so that they all agree on which servers are name servers for the domain and that each of the servers listed as name servers have a copy of the zone.