[NTLUG:Discuss] why does the web site cannot be 'see' from outside (internet)?

[MadHat]

On Mon, 2003-01-06 at 13:23, Greg Edwards wrote:
> m m wrote:
> > 
> > 
> > the problem still happend even I can see the ip A record changed (which 
> > means that Public DNS _really_ updated my A record)
> > 
> > How/what the problem will happen if the serial number don't change?
> > How TTL works on DNS on real world?
> > 
> > 
> >>
> >> Is it possible that the DNS was not reloaded or not updated in a 
> >> reasonable period so the new IP was not broadcast for awhile?
> > 
> > at where? on my box? not quite understand this one.
> > 
> 
> A change in the serial number will force an expire of a record even if 
> the TTL has not expired.  Just cause you change the values in a DNS file 
> does not mean that named will read them.  If your admin does not change 
> the serial number or does not tell named to re-read the files no new IPs 
> will get sent out to the world.

The serial number HAS to be incremented for DNS to be updated if you are
using BIND.  It will not even bother looking at the rest of the file if
the serial has not changed.  The TTL is not for the local machine (the
one serving DNS) it is for the remote machine and how often they should
retain records before checking for updates.  These remote machines don't
really care about the serial directly.

-- 
MadHat at Unspecific.com
`But I don't want to go among mad people,' Alice remarked.
`Oh, you can't help that,' said the Cat: `we're all mad here...'
   -- Lewis Carroll - _Alice's_Adventures_in_Wonderland_