How does it work the Secondary Server?

[Balasubramanyam, Shivakumar]

My bad,

Is this the right forum to ask questions on libresolv ?


>-----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
>