This is what I get step-by step:

#Typing <ifconfig>, I get:
etho inet addr: 100.XX.XX.75 Bcast: 100.XX.XX.255
RX packets: 1100 errors:0 dropped: 0 overruns:0

Obtaining this info, then I type-
# <ping 100.XX.XX.75> (assuming this is my ip address)
I get:
64 bytes from 100.XX.XX.75: icmp_seq=1....68 ttl=65 time=0.156 ms

However, when I try to ping some site by typing-
# <ping www.xyz.com>, I get:
ping: unknown host www.xyz.com

As suggested, then I tried to check my DNS setting at /etc/resolv.conf. The entry there was "nameserver 127.0.0.1"
I vi into /etc/resolv.conf file and changed the entry to "nameserver 100.XX.XX.75". Thinking, this is it but unfortunately still the ping command (ping www.xyz.com) does not work.

Last but not least, then I tried nslookup by typing <nslookup> at the prompt. The note I get was,
"Note: nslookup is deprecated and may be removed from future releases. Consider using the 'dig' and 'host' programs instead."
Following the instructions, I typed <host www.xyz.com> and got the message, "connection timed out; no servers could be reached".

Looking into /etc/nsswitch.conf, I did noted that it displayed
hosts: files dns
.......
.......
.......

Please let me know if you have any other options to recommend.

Thank you so much and regards.........