Domain names resolves at some location, but not at others

[Cobra]

I have two servers, A= (1) 2003 SBS Server, and at a different location B=
(1) 2000 Win server

I host multiple domains, and recently change alot of the servers/OS's and
ips around for the domain resolution.

Now I find that some users at different locations worldwide can not access
their domains.

Server A= Primary DNS = ns1.digitalbackups.net 66.102.110.83 - Runs email
and IIS as well, SBS 2003

Server B=Secondary DNS = 64.36.39.220 , also runs email and IIS, Win2000
Server

one of the domains, www.alkeyman.com

I checked the dnsstuff.com and everything checks ok, and I checked with
dnsdig and all looks ok, any idea why it does not work at some locations,
but not other locations. I notice Comcast users are one main group having a
problem, but I am aware of other ISP's having problems?

Any help or direction would be appreciated,

Thanks,

Cobra

 

[Jonathan de Boyne Pollard]

C> Server A= Primary DNS = 66.102.110.83

This content DNS server is publishing an effectively glueless delegation,
where none of the intermediate domain names used are in-bailiwick, and where
one those domain names, "server01.digitalbackups.local.", does not even
exist at all.

[C:\]dnsgeta server01.digitalbackups.local.
IUZ0031: The domain name "server01.digitalbackups.local." does not exist.
[C:\]

C> Server B=Secondary DNS = 64.36.39.220

This content DNS server is returning "server failure" responses.

[C:\]dnsqry /serverip:64.36.39.220 * alkeyman.com.
[0.0.0.0:0000] -> [64.36.39.220:0035] 30
Header: 0000 1+0+0+0, Q, , query, no_error
Question: alkeyman.com. IN *

[64.36.39.220:0035] -> [0.0.0.0:0000] 30
Header: 0000 1+0+0+0, R, RA|AUTH, query, server_failure
Question: alkeyman.com. IN *

[C:\]