My DNS not always available on the web

[Mark_Andrews at isc.org]

> Thanks Barry.
> 
> So, can a domain contain its own authorative nameservers? In other words coul
> d I
> use ns1.funktion.co.uk and ns2.funktion.co.uk as the name servers for
> funktion.co.uk? If so then I could at least eliminate the bb-online.net stage
> .

	Yes.  This is the DNS used to work before there were a host
	of third party hosted sites.

	Just configure the NS?.FUNKTION.CO.UK as servers for
	funktion.co.uk along with ns?.bb-online.net.  Then add the
	NS records that refer to NS?.FUNKTION.CO.UK (keep the ones
	that refer to ns?.bb-online.net there as well).  Now provide
	new delegation information to CO.UK about FUNKTION.CO.UK,
	they will need A records for NS?.FUNKTION.CO.UK for glue.

	Now all you need to remember is that everytime you change
	the addresses of NS?.FUNKTION.CO.UK you need to update your
	delegation as it contains glue records for NS?.FUNKTION.CO.UK.

	The registrar for CO.UK may provide a seperate method to
	just update the glue records when such a change is made. I
	have not need to deal with them so I don't know.

	Mark
	
> 
> Barry Margolin wrote:
> 
> > In article <7o6gtu$85t$1 at nnrp1.deja.com>,
> > Dan Winchester  <andy.stowell at virgin.net> wrote:
> > >Hi,
> > >
> > >Everyday I seem to get two or three emails from people saying that when
> > >they try and access my site (http://www.freelancers.net) they get a DNS
> > >error. Both DNS servers are based here in my office (as is the
> > >webserver) so I know they are always up as I never have to restart them.
> > >
> > >Ok, so what I generally do is try and track down what DNS they would be
> > >using based on their email address and query it for my domain. More
> > >often than not my query seems to time out with a 'no DNS for host
> > >freelancers.net' type message. But then if I run the same query again it
> > >resolves immediately.
> > >
> > >So, is the problem here that my DNS is just too slow? If so how can I
> > >speed it up? Here are the name servers:
> >
> > I think the problem may be that there are many levels of indirection
> > involved.  Here's a typical scenario when the user's server doesn't have
> > anything related to your domain or ISP in its cache (I'll assume that it
> > does have common TLD and country domain info cached, since that's typical).
> >
> > It queries a root/gtld server for www.freelancers.net.  The server returns
> > a referral:
> >
> > FREELANCERS.net.        172800  NS      NS1.FUNKTION.CO.UK.
> > FREELANCERS.net.        172800  NS      NS2.FUNKTION.CO.UK.
> >
> > Now it needs to look up ns1.funktion.co.uk or ns2.funktion.co.uk.  Most
> > likely it will have the .CO.UK NS records in its cache (per my assumption
> > above), so it doesn't need to start at the root servers again.  It will
> > pick one of the .CO.UK servers and query it.  This will return:
> >
> > funktion.co.uk. 14400   NS      ns1.bb-online.net.
> > funktion.co.uk. 14400   NS      ns2.bb-online.net.
> >
> > Now it has to look up ns1.bb-online.net or ns2.bb-online.net.  It will
> > query one of the root/gtld servers.  This time it gets an answer rather
> > than a referral (I'm not sure why -- these don't seem to be necessary glue
> > records):
> >
> > ns1.bb-online.net.      172800  A       194.168.163.59
> >
> > Now it queries this server and gets:
> >
> > ns1.funktion.co.uk.     86400   A       212.19.75.168
> >
> > and then it finally gets to send the original query to this server, which
> > responds with the answer.
> >
> > All these queries take time, and if it has to go through all of them the
> > querier may time out, especially if there's some network congestion that
> > causes packets to be lost, requiring one or more to be retried (from my
> > desktop in Massachusetts most of these queries took 100-200 ms, so the
> > total time should be around .5-.7 seconds if there are no errors).
> >
> > --
> > Barry Margolin, barmar at bbnplanet.com
> > GTE Internetworking, Powered by BBN, Burlington, MA
> > *** DON'T SEND TECHNICAL QUESTIONS DIRECTLY TO ME, post them to newsgroups.
> > Please DON'T copy followups to me -- I'll assume it wasn't posted to the gr
> oup.
> 
> --
> Dan Winchester
> 
> http://dan.freelancers.net
> mailto:dan at freelancers.net
> 
> http://www.freelancers.net
> 
> 
> 
> 
--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org