FQDNs - are they necessary?

[#1]

Hi. I have 4 machines with static IPs, I have called them Master, slave02, slave03 and slave04. I am trying to install HDP which mentions not using FQDNs might be a problem, so I am thinking of creating fake FQDNs. But does using fake FQDNs make any difference? And can I set my FQDNs to be anything? I can't install using Ambari, please see this question.

[#2 · Accepted solution]

@ed day

You can manage this by maintaining /etc/hosts but whenever IP changes then you have to update the entries in the host file. FQDN is recommended for reasons like changing IP in the environment does not require any changes in the cluster or users does not need to have local /etc/hosts in their env to reach the cluster.

[#3]

@ed day

A fully qualified domain name (FQDN) is the complete domain name for a specific computer, or host, on the Internet. The FQDN consists of two parts: the hostname and the domain name. Ex: hostname.<companyName>.com

Give any similar Name and I don't think you will see any issue.

Ex: If you hostname is hdp234 then give FQDN like hdp234.abc.com

[#4]

@ed day

FQDN is required if you are not using DNS/reverse DNS. See:

http://docs.hortonworks.com/HDPDocuments/Ambari-2.2.2.0/bk_Installing_HDP_AMB/content/_check_dns.htm...

Looks like you are not using DNS, make sure to run the command:

hostname -f 

This should return the <fully.qualified.domain.name> you just set on each node of cluster. And should match /etc/hosts file.

Also make sure the network file contains correct information:

vi /etc/sysconfig/network

NETWORKING=yes
HOSTNAME=<fully.qualified.domain.name>

I recommend you follow prepare environment part of the documentation step by step:

http://docs.hortonworks.com/HDPDocuments/Ambari-2.2.2.0/bk_Installing_HDP_AMB/content/_prepare_the_e...