DNS load balancing issue

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DNS load balancing issue

Satay Epic
Hello,

I've NGINX 1.12-1 running on CentOS 7.2 and being used for DNS load
balancing. However I'm seeing lots of errors in the "dns.log".. I've
no access to the system right now but error was like.. "No response
received from the upstream server" The occurrence of the errors is no
continuous but it's pretty frequent.

The three backend servers are  Windows 2012 R2 DNS servers

I will provide the nginx.conf details soon.

I may have to do some tuning besides upgrade to an appropriate version
I guess.  Can anyone help to suggest/recommend tuning to minimize the
errors or rather not to have them at all?

Thanks
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Re: DNS load balancing issue

Maxim Konovalov
Hi Satay,

On 19.02.2020 09:09, Satay Epic wrote:

> Hello,
>
> I've NGINX 1.12-1 running on CentOS 7.2 and being used for DNS load
> balancing. However I'm seeing lots of errors in the "dns.log".. I've
> no access to the system right now but error was like.. "No response
> received from the upstream server" The occurrence of the errors is no
> continuous but it's pretty frequent.
>
> The three backend servers are  Windows 2012 R2 DNS servers
>
> I will provide the nginx.conf details soon.
>
> I may have to do some tuning besides upgrade to an appropriate version
> I guess.  Can anyone help to suggest/recommend tuning to minimize the
> errors or rather not to have them at all?
>
What I can recommend is to upgrade nginx 1.12 to the most recent 1.17
version (i.e. 1.17.8).   We added tons of improvements into the tcp/udp
load balancing capabilities since 1.12 times.

--
Maxim Konovalov
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Re: DNS load balancing issue

Olaf van der Spek
Hi Maxim,

Thanks for responding. I agree with your recommendation.  I guess a direct
upgrade from 1.12  to 1.16 (free community version) is possible and
shouldn't break it.

I'm preferring 1.61 since it's the latest stable version.  Beside the
upgrade, do you recommend any performance tuning should be done?

Thanks


FYI - This is the error I see in the "dns.log" occurring frequently.

2020/02/19 16:47:28 [error] 19509#0: *4852298929 no live upstreams while
connecting to upstream, udp client: x.x.x.x, server: 0.0.0.0:53, upstream:
"dns_servers", bytes from/to client:50/0, bytes from/to upstream:0/0

This is the nginx.conf ---


worker_processes auto;
error_log /var/log/nginx/error.log;

include /usr/share/nginx/modules/*.conf;

events {
}

stream {
    upstream dns_servers {
        server x.x.x.x:53 fail_timeout=60s;
        server x.x.x.x:53 fail_timeout=60s;
        server x.x.x.x:53 fail_timeout=60s;
    }
    server {
        listen 53  udp;
        listen 53; #tcp
        proxy_pass dns_servers;
        error_log  /var/log/nginx/dns.log info;
        proxy_responses 1;
        proxy_timeout   5s;
    }
}

http {
index index.html;
server {
listen 80 default_server;
server_name _;
access_log /var/log/nginx/access.log;
server_name_in_redirect off;
root  /var/www/default/htdocs;
allow x.x.x.x;
deny all;
location /nginx_status {
    stub_status on;
    access_log off;
}
}
}

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,287053,287069#msg-287069

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