bind configuration to external web server - help required

[Billy]

Our web server is now hosted externally, along with our domain name.  We are 
still using the same domain name space internally, along with the old web 
server.

Internally my users are accessing the internal web server, while externally 
users are accessing the external web server.  I would like decomission the 
internal web server but am trying to change the IP address for the web 
server to the external IP address.

This does not work, and users are still accessing the internal server for 
whatever reason.

Can someone please suggest how they are still accessing the internal server 
when the A record now points to the external DNS.  And how do I set it up so 
users can access the external web?

Cheers,