I found the reason: the whitelist & blacklist are available in the ParentalControl page when I choose AdvancedTab, rather than Basic tab.

I added a few keywords to the Whitelist sometime back. But, I do not find the Whitelist & Blacklist in the ParentalControl page. How come?

Thanks @terziyski. My router is of case #1 type. I added a few keywords to the whitelist, selected a few time slots, and found the parental control working.

@Sunshine I have added a few keywords to the Blocklist. Nothing is added to the Whitelist. I tested by selecting cells in the "Internet Access Time". However, parental control is not enabled for the...

@Sunshine I would like to get another point confirmed from you. By default, in the window "Internet Access Time", no cells are selected. By selecting a cell, does it mean that I am allowing internet...

@Sunshine Thanks for the response. I have selected blacklist with two keywords. And, I did not select whitelist. Please suggest me how to resolve the issue