Unable to install services on my instance.

Question

What am I doing wrong?

I could have swore I am doing it right.

[ec2-user@localhost ~]$ sudo yum install -y telnet-server

Amazon Linux 2023 repository                                                                                                                                                       0.0  B/s |   0  B     00:00    
Errors during downloading metadata for repository 'amazonlinux':
  - Curl error (6): Couldn't resolve host name for https://al2023-repos-default-de612dc2.s3.dualstack.default.amazonaws.com/core/mirrors/2023.2.20231113/x86_64/mirror.list [Could not resolve host: al2023-repos-default-de612dc2.s3.dualstack.default.amazonaws.com]
Error: Failed to download metadata for repo 'amazonlinux': Cannot prepare internal mirrorlist: Curl error (6): Couldn't resolve host name for https://al2023-repos-default-de612dc2.s3.dualstack.default.amazonaws.com/core/mirrors/2023.2.20231113/x86_64/mirror.list [Could not resolve host: al2023-repos-default-de612dc2.s3.dualstack.default.amazonaws.com]
Amazon Linux 2023 Kernel Livepatch repository                                                                                                                                      0.0  B/s |   0  B     00:00    
Errors during downloading metadata for repository 'kernel-livepatch':
  - Curl error (6): Couldn't resolve host name for https://al2023-repos-default-de612dc2.s3.dualstack.default.amazonaws.com/kernel-livepatch/mirrors/al2023/x86_64/mirror.list [Could not resolve host: al2023-repos-default-de612dc2.s3.dualstack.default.amazonaws.com]
Error: Failed to download metadata for repo 'kernel-livepatch': Cannot prepare internal mirrorlist: Curl error (6): Couldn't resolve host name for https://al2023-repos-default-de612dc2.s3.dualstack.default.amazonaws.com/kernel-livepatch/mirrors/al2023/x86_64/mirror.list [Could not resolve host: al2023-repos-default-de612dc2.s3.dualstack.default.amazonaws.com]
Ignoring repositories: amazonlinux, kernel-livepatch
No match for argument: telnet-server
Error: Unable to find a match: telnet-server

Answer

Hi,

This seems to be a DNS error: your EC2 instance cannot access DNS servers to the resolve the name in questions to IP addresses.

2 possible main causes:
*  security group(s) or network ACLs barring access to DNS service (UDP 53)
* internet access to reach the DNS servers not possible: so, either a routing table, a NAT (+ Internet) gateway missing in your VPC.

Please, check those elements!

Best,

Didier

Unable to install services on my instance.

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