[NTLUG:Discuss] Mail server not propagating?

[Bug Hunter]

  In the dns database, you can have as many name servers listed as you
wish.
  
  Essentially, here is what happens on a DNS query.

  machine A asks DNS server B what www.ntlug.org is.  B asks root server C
who handles ntlug.org.  C says use machine D.  Machine D runs the DNS
server for ntlug.org.  It is queried and is asked, "what are your dns
servers? (the SOA)",  then the first server in the  list is asked "what is
www.ntlug.org?"

  From then on, the DNS server B remembers the 1st server in the list
given by Machine D. If D does not respond next time, it goes to the 2nd
server in the list, etc.

  The Root server also gives a list of servers, 1, 2, 3, 4, etc. (I've
seen 6). That list is walked if the initial contact for the DNS server
list fails.

  The TTL (time to live) tells everyone how long B is to remember the
answer from D for www.ntlug.org. (typically 24 hours).  That keeps traffic
down, as the machine A typically will ask 5 to 20 times for the dns
resolution of www.ntlug.org while fetching separate pieces of the page.

  Not to mention the fact that all the friends on the ISP are looking at
NTLUG's pages also. ;)

  The secondary, tertiary, etc, machines all have their named.conf (or
named.boot) files set up as "secondary" for the zone, and pull pages once
a day, typically.  They may pull pages immediately upon realizing a serial
number has changed.  The serial number change is the key to telling other
DNS servers that their saved info is old.

  BTW, how the secondary machines handle being secondary is to put files
in the location you tell them to.  These text files are excellent cleaned
up ip files with data organized rather neatly.  No comments, though.  But
they do indicate to you how you should do it. :)

bug

 

On Fri, 12 Jul 2002 brian at pongonova.net wrote:

> On Fri, Jul 12, 2002 at 02:58:24PM -0500, Bug Hunter wrote:
> > 
> >   the first name server in the list is the master name server
> >   the second name server in the list is the secondary name server
> >   the third """" tertiary
> >   the fourth """" quatentary  (sp?)
> 
> Well, the move to being "PC" by downgrading master and slave has just made the
> confusion worse.  One master/many slaves is a pretty straightforward concept...but
> how can one have one primary/many secondaries???
> 
>   --Brian