add i/o timeout

Author: alt-key

articles/azure-arc/resource-bridge/troubleshoot-resource-bridge.md

@@ -263,6 +263,16 @@ To check if the DNS server is able to resolve an address, from a machine where w
 
 ```Resolve-DnsName -Name "http://aszhcitest01.company.org:55000" -Server "<dns-server.com>"```
 
+### Not able to connect - i/o timeout
+
+When deploying Arc resource bridge, if you receive an error with `errorCode` as `PostOperationsError`, `errorResponse` as code `GuestInternetConnectivityError` with keywords `i/o timeout` and `read udp`, then the error may be caused by the appliance VM IPs not having reachability to the DNS server(s) to resolve the MOC cloud agent address endpoint specified in the error. 
+
+Error example: 
+
+```{ _errorCode_: _PostOperationsError_, _errorResponse_: _{\n\_message\_: \_{\\n  \\\_code\\\_:\\\_GuestInternetConnectivityError\\\_,\\n\\\_message\\\_:\\\_Not able to connect to http://aszhcitest01.company.org:55000. Error returned: action failed after 5 attempts: Get \\\\\\\_http://aszhcitest01.company.org:55000\\\\\\\_: dial tcp: lookup aszhcitest01.company.org on 127.0.0.53:53: read udp 127.0.0.1:32975-\\u003e127.0.0.53:53: i/o timeout. Arc Resource Bridge network and internet connectivity validation failed: cloud-agent-connectivity-test. 1. Please check your networking setup and ensure the URLs mentioned in : https://aka.ms/AAla73m are reachable from the Appliance VM.   2. Check firewall/proxy settings\\\_\\n }\_\n}_ }```
+
+To resolve the error, work with your network administrator to allow the appliance VM IPs to reach the DNS server(s).
+
 ### Authentication handshake failure
 
 When running an `az arcappliance` command, you might see a connection error: `authentication handshake failed: x509: certificate signed by unknown authority`