SOLUTION:

a. Go to terminal

b. Open /etc/koha/koha-conf.xml with an editor
      Eg. [root@localhost~]# vim /etc/koha/koha-conf.xml
      Uncomment following lines:
      <listen id="publicserver">tcp:@:9998</listen>
      <server id="publicserver" listenref="publicserver">
      <server info id="publicserver">
       save and quit

c. Now restart Zebra:
    sh /usr/share/koha/bin/koha-zebra-ctl.sh restart

d. Check connectivity
      [root@localhost~]# yaz-client ip-address:9998/biblios
     OUTPUT:
      Connecting ok.
      Sent initrequest.
      Connection accepted by v3 target.
      ID  : 81
      Name    : Zebra information Server/GFS/YAZ
      Version : 2.0.53/4.2.51
      d5ea9ffb52a014f258ac9e41ca34a6d9ba4b45c8
      Option  : search present delSet triggerResourceCtrl scan sort
      extendedServices
      namedResultSets  Elapsed: 0.005532
      Z>q

e. service iptables stop

f. setenforce 0

g. service httpd restart & mysqld restart

Now search the record from koha zebra search, if it is still not fetching records then contact to Network admin and ask him to open the port for your koha machine.