Configuring Network Names

To ensure that the members of the cluster can communicate with each other, do the following on every system.
  1. Set the hostname of each system to a unique name (not localhost). For example: 
    $ sudo hostname myhost-1
  2. Make sure the /etc/hosts file on each system contains the IP addresses and fully-qualified domain names (FQDN) of all the members of the cluster.

    If you are using DNS, storing this information in /etc/hosts is not required, but it is good practice.

  3. Make sure the /etc/sysconfig/network file on each system contains the hostname you have just set (or verified) for that system, for example myhost-1.
  4. Check that this system is consistently identified to the network:
    1. Run uname -a and check that the hostname matches the output of the hostname command.
    2. Run /sbin/ifconfig and note the value of inet addr in the eth0 entry, for example: 
      $ /sbin/ifconfig
eth0      Link encap:Ethernet  HWaddr 00:0C:29:A4:E8:97  
          inet addr:172.29.82.176  Bcast:172.29.87.255  Mask:255.255.248.0
...
    3. Run host -v -t A `hostname` and make sure that hostname matches the output of the hostname command, and has the same IP address as reported by ifconfig for eth0; for example: 
      $ host -v -t A `hostname`
Trying "myhost.mynet.myco.com"
...
;; ANSWER SECTION:
myhost.mynet.myco.com. 60 IN
A
172.29.82.176
  5. For MRv1: make sure conf/core-site.xml and conf/mapred-site.xml, respectively, have the hostnames – not the IP addresses – of the NameNode and the JobTracker. These can be FQDNs (for example myhost-1.mynet.myco.com), or unqualified hostnames (for example myhost-1). See Customizing Configuration Files and Deploying MapReduce v1 (MRv1) on a Cluster.
  6. For YARN: make sure conf/core-site.xml and conf/yarn-site.xml, respectively, have the hostnames – not the IP addresses – of the NameNode, the ResourceManager, and the ResourceManager Scheduler. See Customizing Configuration Files and Deploying MapReduce v2 (YARN) on a Cluster.
  7. Make sure that components that depend on a client-server relationship – Oozie, HBase, ZooKeeper – are configured according to the instructions on their installation pages: