Receiving a "cannot resolve <hostname>": unknown host

  • KM03711840
  • 22-Sep-2020
  • 22-Sep-2020

Summary

Receiving a "cannot resolve ": unknown host

Error

When attempting to install the Interset software via the Interset installation wizard, the following error is outputted:

ERROR: ssh: Could not resolve hostname <INTERSET_NODE_FQDN>: Name or service not known ERROR: ssh: Could not resolve hostname <INTERSET_NODE_FQDN>:: Name or service not known

 

 

 

Cause

This is normally caused by a DNS resolution issue, or the node FQDN was entered incorrectly into the Interset config file.

Fix

#Note: in the following writeup Ambari = Monitoring Node 

Resolution Steps

There are several steps to take in order to validate and ensure Ambari has access to all necessary nodes in the Interset cluster. Please perform the steps in the following order:

1. Validate each FQDN node
2. Ping other node(s)/system(s)

3. Check DNS configuration

Validate each FQDN node

1.      Log on to the Monitoring node as the Interset user

2.      On the Monitoring node, type in the following command to navigate to the config file that is located in

/opt/interset/installer/etc (or /tmp/interset_installer/etc/ in older releases than 5.9.x)

3.      In the directory open up the config file using the desired text editing tool (vi is usually a safe bet)

4.      Validate the FQDN values that was entered into MONITORING (or AMBARI), COMPUTE, MASTER, REPORTING, SEARCH, STREAM.

5.      Once validated and /or modified (if required), save and exit the config file

Ping other node(s)/system(s)

1.      Log on to the Ambari node as the Interset user

2.      On the Ambari node, attempt to ping other node(s) in the Interset cluster, along with systems that are NOT in the Interset cluster. The command to ping is:

ping <node_FQDN>

Check DNS configuration

1. Log on to the Monitoring node as the Interset user
2. Type in the following command to display the content of the conf that is located in /etc/ directory:

sudo cat /etc/resolv.conf

3. Ensure the DNS configuration outputted is pointed to the correct DNS Servers within the environment.

4. If DNS is incorrect, edit the conf that is located in /etc with the desired editing tool
5. Once configuration changes are made, save and exit the conf file