DNS UDP Load Balancer using Nginx Rumi, June 14, 2018March 12, 2023 The plan is to build a DNS- UDP load balancer DNS recursive server (actually forwarding service). The design logic is simple- On client side a public recursive+forwarding DNS IP –> hits the Nginx Load Balancers –> sends traffic to Google Public DNS/IBM Public DNS/Own recursive DNS/OpenDNS. The configuration is quite simple on Nginx Load Balancer, the core configuration content is pretty straight forward: # Load balance UDP-based DNS traffic across two servers stream { upstream dns_upstreams { server 192.168.136.130:53; server 192.168.136.131:53; } server { listen 53 udp; proxy_pass dns_upstreams; proxy_timeout 1s; proxy_responses 1; error_log logs/dns.log; } } However, the above configuration is pretty confusing, as where to put it? Should it be in nginx.conf or under /sites-available/default or /conf.d/default.conf… so many options. But finally the riddle was over, as I had to put the syntax inside, nginx.conf file. So, here goes my final/complete nginx.conf file- # For more information on configuration, see: # * Official English Documentation: http://nginx.org/en/docs/ # * Official Russian Documentation: http://nginx.org/ru/docs/ user nginx; worker_processes auto; error_log /var/log/nginx/error.log; pid /var/run/nginx.pid; # Load dynamic modules. See /usr/share/nginx/README.dynamic. include /usr/share/nginx/modules/*.conf; events { worker_connections 1024; } http { log_format main '$remote_addr - $remote_user [$time_local] "$request" ' '$status $body_bytes_sent "$http_referer" ' '"$http_user_agent" "$http_x_forwarded_for"'; access_log /var/log/nginx/access.log main; sendfile on; tcp_nopush on; tcp_nodelay on; keepalive_timeout 65; types_hash_max_size 2048; include /etc/nginx/mime.types; default_type application/octet-stream; # Load modular configuration files from the /etc/nginx/conf.d directory. # See http://nginx.org/en/docs/ngx_core_module.html#include # for more information. ##################################### # Load balance UDP-based DNS traffic across two servers #stream { # upstream dns_upstreams { # server 8.8.8.8:53; # server 9.9.9.9:53; # } # server { # listen 53 udp; # proxy_pass dns_upstreams; # proxy_timeout 1s; # proxy_responses 1; # error_log logs/dns.log; # } #} ##################################3## include /etc/nginx/conf.d/*.conf; } stream { upstream dns_upstreams { server 8.8.8.8:53; server 9.9.9.9:53; } server { listen 53 udp; proxy_pass dns_upstreams; proxy_timeout 1s; proxy_responses 1; error_log /var/log/dns.log; } } // Update on CentOS You need to install stream binary in order to make this work. yum install nginx-mod-stream Src: Announcing UDP Load Balancing in NGINX and NGINX Plus Networking Load BalancenginxUDP Load Balance