Refer to RFC 1918 and list the IP address blocks that are reserved for use in private networks. Why is there a need to specify IP addresses for private networks?

What will be an ideal response?

The Internet Assigned Numbers Authority (IANA) has reserved the following three blocks of the IP address space for private internets:
10.0.0.0 - 10.255.255.255 (10/8 prefix) – 24 bit block
172.16.0.0 - 172.31.255.255 (172.16/12 prefix) – 20 bit block
192.168.0.0 - 192.168.255.255 (192.168/16 prefix) – 16 bit block
The need to specify this comes from the fact that two hosts on the internet can have the same IP
addresses if the private networks are allowed to keep any IP address they want. An enterprise that requests IP addresses for its external connectivity will never be assigned addresses from the blocks defined above. The address space can thus simultaneously be used by many enterprises Because private addresses have no global meaning, routing information about private networks shall not be propagated on inter-enterprise links, and packets with private source or destination
addresses should not be forwarded across such links. Routers in networks not using private address space, especially those of Internet service providers, are expected to be configured to reject (filter out) routing information about private networks. If such an enterprise would later connect to the Internet, this could potentially create very serious problems, as IP routing cannot provide correct operations in presence of ambiguous addressing.