Similar idea... It sounds like the change in the NIC hardware caused a loss
of connectivity because of
The Address Resolution Protocol (ARP) information in the local
router/switch¹s cache.
DNS relates a name record to an IP address and ARP associates the IP address
with the
Physical hardware address burned in the NIC.  The router/switch still had
the old address stored because
It resolves, caches, and refreshes ARP information just like DNS.  A simple
ARP flush probably fixed the problem.

Your description is correct below... a submitted DNS change through your
data centre host
Can/will be reflected immediately after they do it for all subsequent DNS
resolution requests.
All clients/end users that have previously completed a DNS resolution will
have bad info cached
Until it expires and they resolve the name again.  The redundancy and
reliability built into the DNS
System also introduces a certain amount of latency for changes and updates.

Ed


On 5/19/10 7:57 PM, "keith smith" <klsmith2020@yahoo.com> wrote:

> 
> This is kind of fizzy to me.  I'm glad you brought it up.  I did experience
> this 6 to 9 month ago when the data center chanced the NIC card.  I think they
> had to flush some buffers in their routers so the new MAC address could be
> found and cached if I recall correctly.
> 
> We are in a data center and use their DNS.  So I'm thinking the request goes
> to the root server then to the data center's DNS and it tells the client what
> the IP address is.  So if the Data Center's DNS is changed to point to a new
> IP for our domain then that would be instantaneous or would the client and
> everyone along the way cache the IP?
> 
>