Windows Ec2 Instance often Doing DNS query with Public DNS Resolver.

Question

Hi Team. My Windows ec2 instance instance is often communication with public DNS resolvers (google, azure, Cloudflare) instead of AWS VPC's DNS resolver. EC2 instance's Network settings are set to automatic (DHCP) and unchanged. can you please help me find why my ec2 is communication with public DNS resolvers (google, azure, Cloudflare).

findings source: Guard Duty Findings and VPC flow logs. note: This not my windows DNS Server

Regards, Jayaprakash M

findings source: Guard Duty Findings and VPC flow logs.
note: This not my windows DNS Server

Regards, Jayaprakash M

Answer

Navigate to chrome://flags/
Look for #enable-async-dns 
Async DNS enabled/disabled displays whether the server uses its own asynchronous DNS resolver instead of the operating system's synchronous resolver.  This is by default disabled normally so might not be the actual issue, it could be some other service/app installed that could be sending these queries too.

Answer

I believe you asked the same question a week ago.

One thing comes to mind. Do you have Chrome installed??

As it can ignore the OS dns settings and use it’s own DNS servers.

https://www.reddit.com/r/chrome/comments/pexxds/google_chrome_ignores_other_dns_servers_in_system/

Windows Ec2 Instance often Doing DNS query with Public DNS Resolver.

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