AWS Client VPN - Cannot resolve host

Question

Since 6th Feb, our AWS Clients have been generating errors such as

```
2023-02-06 10:33:48.752 +00:00 [DBG] >LOG:1675679628,N,RESOLVE: Cannot resolve host address: xxxxxxxxxxxx.cvpn-endpoint-xxxxxxxxxxxx.prod.clientvpn.eu-west-1.amazonaws.com:443 (No such host is known. )
```
We have upgraded the AWS Client installs to 3.2.0 but get the same error, even on new client endpoints

Nslookups return non-existent domain
```
nslookup cvpn-endpoint-xxxxxxxxxxxxxxxxx.prod.clientvpn.eu-west-1.amazonaws.com
Server:  UnKnown
Address:  fd2a:6118:11c7:0:681:9bff:fe59:fc70

*** UnKnown can't find cvpn-endpoint-xxxxxxxxxxxxxxxxx.prod.clientvpn.eu-west-1.amazonaws.com: Non-existent domain
```

I also get cannot resolve errors in CloudShell

Answer

Hello,

Here if from your nslookup output it clearly says that there is an issue over DNS server in your machine.
Server:  UnKnown
Address:  fd2a:6118:11c7:0:681:9bff:fe59:fc70

So you are not able to resolve public domain name itself.

Please check resolv.conf file or system DNS server which should be configured properly and it should be able to resolve public Domain

% cat /etc/resolv.conf

There should be correct nameserver configuration to resolve the URL.

Common tshoot  : https://docs.aws.amazon.com/vpn/latest/clientvpn-admin/troubleshooting.html

AWS Client VPN - Cannot resolve host

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