UDP Support on Network Load Balancer

Hosting a DNS service with Network Load Balancer

Use Cases and Setup

You can now migrate your on-premise DNS application to AWS. With UDP support on Nework Load Balancer(NLB), you can centralize your DNS service infrastructure to achieve operational efficiencies such as scale, manage downtime or upgrades, and share one fixed IP externally.

In this demo, the "network.exampleloadbalancer" Network Load Balancer (NLB) has a TPC/UDP listener which listens on port 53 for DNS queries. There is a TCP/UDP target group which has many DNS targets behind the Network Load Balancer.

You can create a DNS A record for a subdomain name of "demo.internal" through the input form below.

Once the DNS record is created, you can query the Network Load Balancer to resolve the subdomain through either TCP or UDP.

The DNS A record that you create is only valid for 2 minutes. After that, it will be deleted from the DNS servers

Also, you can use the following dig commands to resolve the default A records without creating one of your own.

DNS Demo

What happen when you send a DNS query to the Network Load Balancer?

1. DNS Clients send a DNS query to the Network Load Balancer

2. The Network Load Balancer has a TCP_UDP listener which listens on port 53 of both TCP and UDP traffic. It forwards the DNS request to a target group whose traffic routing protocol is also TCP_UDP on port 53.

3. The backend DNS server resolves the DNS require by looking up in its hosts file and sends a DNS response