DNS record, query returns different result.

Scenario:

Names resolution not consistence

A friend of mine complaining that the link to his company web app sometime working and sometime not.

Details:

http://myapp.hiscompany.com (accessible)

After few minutes / from other PC/host

http://myapp.hiscompany.com (page not found)

Resolutions:

Figure out whether DNS query such return consistence result. Using host and dig command from Linux and nslookup from Windows machine return no result.

Using web based lookup http://zoneedit.com/lookup.html returns result.

Nailing down by querying directly from hiscompany DNS server. The first server (ns1.hiscompany.com) resides within the company network while the second server (ns2.hiscompany.com) hosted at ISP.

Querying on first DNS server return result while not on the second server.
The record is not sync on both servers. It should by default the records are synced by zone transfer facility if using BIND in Linux.

Fact: 
DNS servers retrieve information from other DNS.