How does it work the Secondary Server?

[Mark Andrews]

> My bad,
> 
> Is this the right forum to ask questions on libresolv ?

	Yes.
 
> >-----Original Message-----
> >From: bind-users-bounce at isc.org [mailto:bind-users-bounce at isc.org] On
> >Behalf Of Mark Andrews
> >Sent: Monday, April 02, 2007 3:32 PM
> >To: Balasubramanyam, Shivakumar
> >Cc: Ricardo Martinez; bind-users at isc.org
> >Subject: Re: How does it work the Secondary Server?
> >
> >
> >	The original question was about listed nameservers for
> >	the zone not nameservers listed in resolv.conf.
> >
> >> Ricardo, ALL,
> >>
> >> I have the exact same problem (case b.)
> >>
> >> I used libresolv library and here is the behavior I found.
> >>
> >> Actually, in case b, there are again two cases.
> >> 1. Machine is Up but named is down.
> >> 2. Machine is down.
> >>
> >> In first case,
> >> 1. Using UDP.
> >> 	Every request goes is to primary/secondary in a round robin
> >> fashion.
> >> 	Without lowest timeout of 1 sec, this is still very slow.
> >> 	I could not figure out how to tell the client library to stick
> >> to one 	that 	last succeeded.
> >
> >	Actually it should get a ICMP port unreachable back which
> >	with a connected UDP socket will cause libresolv to move
> >	onto the next listed server.  Libresolv uses connected UDP
> >	sockets to talk to the recursive servers.
> >
> >> 2. Using TCP.
> >> 	Much faster than UDP as it quickly gets a RESET packet for a SYN
> >> request.
> >> 	TCP_STAYOPEN did not work in this case.I was expecting to use
> >> the same 	connection for additional requests
> >>
> >> Second case,
> >>
> >> 1. Using UDP,
> >> 	same behavior
> >> 2. Using TCP
> >> 	The SYN packets are not responded and tcp stack takes about 5
> >> minutes to fail on the fist machine. SYN_ACK_RETRIES was set to 5. I
> got
> >> to down to  less than 30 seconds  by setting the parameter to 2.
> >> So if you are performing two queries, it takes 10 minutes to succeed.
> >>
> >> But when I use the "host" or "dig" application, it is really fast in
> all
> >> the above scenarios.
> >>
> >> Any idea what I am doing wrong?
> >>
>> Thanks,
> >> Shiva
> >>
> >> >-----Original Message-----
> >> >From: bind-users-bounce at isc.org [mailto:bind-users-bounce at isc.org]
> On
> >> >Behalf Of Ricardo Martinez
> >> >Sent: Monday, April 02, 2007 2:13 PM
> >> >To: bind-users at isc.org
> >> >Subject: How does it work the Secondary Server?
> >> >
> >> >Hello list.
> >> >	I have a general question about how the seconday/slave server
> >> works.
> >> >Please correct me if i'm wrong.
> >> >I have two DNS bind servers, one is the primary server and the
> other,
> >> as
> >> >you could guess, is the secondary/slave server.   My question is
> >> related to
> >> >the way the requests are procesed in
> >> >
> >> >a.- Normal Situation
> >> >b.- Failure of the Primary Server
> >> >c.- Failure of the Secondary Server
> >> >
> >> >Can someone explain to me how this work, i'm a little bit confused
> >> >especially when a failure occurs.
> >> >For example in normal situation the request from the root servers
> >> arrives
> >> >50% to my primary server and 50% to my secondary, isn't?  If so,
> what's
> >> the
> >> >idea of a secondary server if primary goes down? it will keep
> receiving
> >> >requests even if the server is down?
> >> >
> >> >Hope that someone could explain to me this.
> >> >Thanks in advance
> >> >
> >> >Regards,
> >> >Ricardo.-
> >> >
> >>
> >>
> >--
> >Mark Andrews, ISC
> >1 Seymour St., Dundas Valley, NSW 2117, Australia
> >PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at isc.org
> >
> 
> 
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at isc.org