Support Questions
Find answers, ask questions, and share your expertise
Announcements
Alert: Welcome to the Unified Cloudera Community. Former HCC members be sure to read and learn how to activate your account here.

How important is the host command for installation and working of the cluster?

Highlighted

How important is the host command for installation and working of the cluster?

Explorer

ubuntu@hadoop:~$ hostname host-192-130-3-18.openstacklocal

ubuntu@hadoop:~$ host host-192-130-3-18.openstacklocal

Host host-192-130-3-18.openstacklocal not found: 3(NXDOMAIN)

ubuntu@hadoop:~$ host 192.130.3.18 Host 18.3.130.192.in-addr.arpa. not found: 3(NXDOMAIN)

ubuntu@hadoop:~$

I feel my hdp is not working because of this. Can someone comment on it. I can edit the hostname by hostname abc

but i dont know how it work. Your valuable comments will be highly appreciated.

I can do a hostname and it returns me

4 REPLIES 4

Re: How important is the host command for installation and working of the cluster?

Super Collaborator
@irfan aziz

host command is a dns utility , just like nslookup. Do you have DNS configured? You can try the command

#getent hosts <hostname>

Can you please explain more about hdp is not working, what error you see when you try to start services?

Re: How important is the host command for installation and working of the cluster?

Super Mentor

irfan aziz

In addition to rguruvannagari comment.

- When you get "Host 218.3.130.192.in-addr.arpa. not found: 3" this it is not good as Because all the hosts in your system must be configured for both forward and and reverse DNS. If you are unable to configure DNS in this way, you should edit the /etc/hosts file on every host in your cluster to contain the IP address and Fully Qualified Domain Name of each of your hosts.

Hadoop relies heavily on DNS, and as such performs many DNS lookups during normal operation. it is not must to have the "host" utlility installed. But it is better to have it.

Please see: 1. http://docs.hortonworks.com/HDPDocuments/Ambari-2.4.2.0/bk_ambari-installation/content/check_dns.htm...

2. http://docs.hortonworks.com/HDPDocuments/Ambari-2.4.2.0/bk_ambari-installation/content/set_the_hostn...

Re: How important is the host command for installation and working of the cluster?

Explorer

@Jay SenSharma @rguruvannagari Than you guys. Yes forward and reverse dns lookup is important for multi cluster but i for me it was not necessary.. However, i am working on a single node cluster(virual server on cloud). It has two ip address one is called floating ip. That is used to communicate outside the machine. The other is its actual ip. So I was using floating ip in the hosts file. That was failing the resource manager with the error given below. Now it sounds good and RM is running fine and i could run a MR example job too.

INFO client.RMProxy: Connecting to ResourceManager at hadoop.localdomain/127.0.1.1:805016/12/21 11:58:20 INFO ipc.Client: Retrying connect to server: hadoop.localdomain/127.0.1.1:8050. Already tried 0 time(s); retry policy is RetryUpToMaxi sleepTime=1000 MILLISECONDS)

Re: How important is the host command for installation and working of the cluster?

Super Mentor

@irfan aziz

You mentioned "That was failing the resource manager with the error given below."

However the output that you posted is INFO message. DO you see any error as well.

Don't have an account?
Coming from Hortonworks? Activate your account here