Hi Sarbjeet,
Thanks for your swift response.
The entries in Host file are as follows :
wdisp/system_0 = SID=<Front end SID>, EXTSRV=<Front end host>:<Front end port>, SRCSRV=*:80, SRCURL=/sap/opu/odata, CLIENT=<front end client>
wdisp/system_1 = SID=<Front end SID>, EXTSRV=<Front end host>:<Front end port>, SRCSRV=*:80,SRCURL=/sap/public/bc/;/sap/bc/, CLIENT=<front end client>
wdisp/system_2 = SID=<Back end SID>, EXTSRV=<Back end host>:<Back end port>, SRCSRV=*:80,SRCURL=/sap/es/ina/;/ENTERPRISE_SEARCH/, CLIENT=<back end client>
Kindly let us know if we need to make any changes in the front end's Fiori search so that the request hits the back end through the web dispatcher