Round robin load distribution among servers does not work properly
Mallappa Pallakke
pallakke at gmail.com
Tue Apr 7 02:15:26 UTC 2009
Hi Mark,
I do not see any additional section in the response. Can you please
tell me what exactly you are asking me to change?
I selected cyclic instead of random since I want my client requests
to go to servers in exactly round-robin order. Please tell is there
anything wrong with this?
Thanks,
Mallappa Pallakke
On Mon, Apr 6, 2009 at 6:55 PM, Mark Andrews <Mark_Andrews at isc.org> wrote:
>
> In message <96c8e9660904061734t61414549o22a535e681f5866b at mail.gmail.com>, Mallappa Pallakke
> writes:
>> Hi,
>>
>> I tried with 9.5.1.P2, but still I am not getting the expected round
>> robin results:
>>
>> Please see below my named.conf and zone file:
>>
>> named.conf:
>> =========
>> options {
>> directory "/var/named";
>>
>> // Uncommenting this might help if you have to go through a
>> // firewall and things are not working out. But you probably
>> // need to talk to your firewall admin.
>>
>> //query-source port 53;
>>
>> rrset-order {
>> order cyclic;}; // fixed, random, cyclic
>> };
>>
>> zone "mycompany.com" {
>> type master;
>> // notify no;
>> file "db.mycompany.com";
>>
>> allow-update { any; };
>> // allow-update { 127.0.0.1; };
>> notify yes;
>> };
>>
>>
>> db.mycompany.com:
>> ===============
>> $ORIGIN .
>> $TTL 0 ;
>> mycompany.com IN SOA www.mycompany.com. hostmaster.mycompany.com. (
>> 199813404 ; serial
>> 1 ; refresh (1 second)
>> 1 ; retry (1 second)
>> 1 ; expire (1 second)
>> 1 ; minimum (1 second)
>> )
>> NS www.mycompany.com.
>> $ORIGIN mycompany.com.
>> localhost A 127.0.0.1
>> $TTL 0 ;
>> www A 10.10.68.1
>> A 10.10.68.2
>> A 10.10.68.3
>> A 10.10.68.4
>
> Change the nameservers name to be something other than
> www.mycompany.com.
>
> www.mycompany.com is being retrieved twice once for the
> answer section and once for the additional section. Each
> retrieval rotates the RRset once. The latter gets thrown
> away when named supresses duplicate RRsets in the answer
> so you see 2 rotations and 2 divides equally into 4.
>
> B.T.W. one should choose "random" rather than "round-robin" if
> you want uniform load on failure.
>
> Mark
>
>> I always get following answers repeatedly. Not getting 10.10.68.2 and
>> 10.10.68.3 as top records in response messages:
>> =================================================
>> atcafs-n4s1:/kwlogs/msp# dig www.mycompany.com
>>
>> ; <<>> DiG 9.3.2 <<>> www.mycompany.com
>> ;; global options: printcmd
>> ;; Got answer:
>> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 13961
>> ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 1, ADDITIONAL: 0
>>
>> ;; QUESTION SECTION:
>> ;www.mycompany.com. IN A
>>
>> ;; ANSWER SECTION:
>> www.mycompany.com. 0 IN A 10.10.68.4
>> www.mycompany.com. 0 IN A 10.10.68.1
>> www.mycompany.com. 0 IN A 10.10.68.2
>> www.mycompany.com. 0 IN A 10.10.68.3
>>
>> ;; AUTHORITY SECTION:
>> mycompany.com. 0 IN NS www.mycompany.com.
>>
>> ;; Query time: 1 msec
>> ;; SERVER: 10.10.68.1#53(10.10.68.1)
>> ;; WHEN: Sun Apr 6 00:21:07 2008
>> ;; MSG SIZE rcvd: 113
>>
>>
>> =================================================
>>
>> atcafs-n4s1:/kwlogs/msp# dig www.mycompany.com
>>
>> ; <<>> DiG 9.3.2 <<>> www.mycompany.com
>> ;; global options: printcmd
>> ;; Got answer:
>> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 65208
>> ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 1, ADDITIONAL: 0
>>
>> ;; QUESTION SECTION:
>> ;www.mycompany.com. IN A
>>
>> ;; ANSWER SECTION:
>> www.mycompany.com. 0 IN A 10.10.68.2
>> www.mycompany.com. 0 IN A 10.10.68.3
>> www.mycompany.com. 0 IN A 10.10.68.4
>> www.mycompany.com. 0 IN A 10.10.68.1
>>
>> ;; AUTHORITY SECTION:
>> mycompany.com. 0 IN NS www.mycompany.com.
>>
>> ;; Query time: 1 msec
>> ;; SERVER: 10.10.68.1#53(10.10.68.1)
>> ;; WHEN: Sun Apr 6 00:21:09 2008
>> ;; MSG SIZE rcvd: 113
>>
>> ===================================================
>>
>>
>> Please let me know anything is missing.
>>
>> Regards,
>> Mallappa Pallakke
>>
>>
>> On Sun, Apr 5, 2009 at 8:55 AM, Kirk <bind at kirkb.net> wrote:
>> > Mallappa Pallakke wrote:
>> >>
>> >> Hi,
>> >>
>> >> I was trying to do load balancing of client request among
>> >> configured servers using internal DNS server, I get proper load
>> >> balaning (DNS response with top most IP address going with proper
>> >> round robin fashio) for odd number of IP addresses. But it does not
>> >> give same bevior for even number of IP addresses.
>> >>
>> >> For example:
>> >>
>> >> If I have configured x.y.z.1, x.y.z.2, x.y.z.3, I get following
>> >> combinations in dig response:
>> >>
>> >> x.y.z.1
>> >> x.y.z.2
>> >> x.y.z.3
>> >>
>> >> x.y.z.2
>> >> x.y.z.3
>> >> x.y.z.1
>> >>
>> >> x.y.z.3
>> >> x.y.z.1
>> >> x.y.z.2
>> >>
>> >> And this repeats, giving round robin distribution.
>> >>
>> >> However, if I add one more IP address to the zone list (x.y.z.4), I
>> >> get only following combinations:
>> >>
>> >> x.y.z.1
>> >> x.y.z.2
>> >> x.y.z.3
>> >> x.y.z.4
>> >>
>> >> and
>> >>
>> >> x.y.z.3
>> >> x.y.z.4
>> >> x.y.z.1
>> >> x.y.z.2
>> >>
>> >> It gets repeated. I will never get x.y.z.2 and x.y.z.4 as top entries
>> >> in this response.
>> >>
>> >> Can anybody tell me why this limitation and is there any sollution to
>> >> resove this problem?
>> >>
>> >> Thanks in advance.
>> >>
>> >> Mallappa
>> >
>> >
>> > Not sure what version of BIND you are using, but here I am using 9.5.1-P2.
>> > I just loaded a zone with 10 www records and different IP's and they are
>> > handed out round robin just fine.
>> >
>> > The idea of using DNS for load balancing has been brought up here so many
>> > times its hard to count. The answer is always the same. DNS was *never*
>> > meant to provide this functionality. Spend the big bucks and get a device
>> > meant to do *load balancing*.
>> >
>> > Search the archive for previous threads on this subject.
>> > http://marc.info/?l=bind9-users&w=2&r=1&s=load+balancing&q=b
>> >
>> _______________________________________________
>> bind-users mailing list
>> bind-users at lists.isc.org
>> https://lists.isc.org/mailman/listinfo/bind-users
> --
> Mark Andrews, ISC
> 1 Seymour St., Dundas Valley, NSW 2117, Australia
> PHONE: +61 2 9871 4742 INTERNET: Mark_Andrews at isc.org
>
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