To the mapred-site.xml file on every host in your cluster, you must add the following
                    information:
Table 13.5. mapred-site.xml
| Property Name | Property Value | Description | Final | 
|---|---|---|---|
| mapreduce.jobtracker.kerberos.principal | jt/_HOST@EXAMPLE.COM | Kerberos principal name for the JobTracker | |
| mapreduce.tasktracker.kerberos.principal | tt/_HOST@EXAMPLE.COM | Kerberos principal name for the TaskTracker. _HOSTis replaced by the host name of the
                                    task tracker. | |
| mapreduce.jobtracker.keytab.file |  /etc/security/keytabs/jt.service.keytab
                                     | The keytab for the JobTracker principal | |
| mapreduce.tasktracker.keytab.file | /etc/security/keytabs/tt.service.keytab | The keytab for the Tasktracker principal | |
| mapreduce.jobhistory.kerberos.principal Note: cluster variant | jt/_HOST@EXAMPLE.COM | Kerberos principal name for JobHistory. This must map to the same user as the JT user. | true | 
| mapreduce.jobhistory.keytab.file Note: cluster variant | /etc/security/keytabs/jt.service.keytab | The keytab for the JobHistory principal | 
The XML for these entries:
<property>  
        <name>mapreduce.jobtracker.kerberos.principal</name>  
        <value>jt/_HOST@EXAMPLE.COM</value>  
        <description>Kerberos principal name for the JobTracker   </description> 
</property>   
<property>  
        <name>mapreduce.tasktracker.kerberos.principal</name>   
        <value>tt/_HOST@EXAMPLE.COM</value>  
        <description>Kerberos principal name for the TaskTracker.
        "_HOST" is replaced by the host name of the task tracker.  
        </description> 
</property>      
 
<property>   
        <name>mapreduce.jobtracker.keytab.file</name>   
        <value>/etc/security/keytabs/jt.service.keytab</value>   
        <description>       
        The keytab for the jobtracker principal.   
        </description>   
</property>    
<property>   
        <name>mapreduce.tasktracker.keytab.file</name>   
        <value>/etc/security/keytabs/tt.service.keytab</value>    
        <description>The filename of the keytab for the task
        tracker</description>  
</property>    
<property>    
        <name>mapreduce.jobhistory.kerberos.principal</name>     
        <!--cluster variant -->  
        <value>jt/_HOST@EXAMPLE.COM</value>    
        <description> Kerberos principal name for JobHistory. This must map to 
               the same user as the JT user. )</description>  
</property>    
<property>   
        <name>mapreduce.jobhistory.keytab.file</name>     
        <!--cluster variant -->   
        <value>/etc/security/keytabs/jt.service.keytab</value>   
        <description>The keytab for the JobHistory principal
        principal.</description>  
</property>   

