UGC NET CSE | June 2019 | Part 2 | Question: 88

Question

What percentage $(\%)$ of the IPv4, IP address space do all class C addresses consume?

• A. $12.5 \%$
• B. $25 \%$
• C. $37.5 \%$
• D. $50 \%$

Answer 1

Class C Addresses 

Total No. of IpV4 addresses possible               = $  2^(32) $

Total No of IPv4 address belong to Class C    =$ 2^(29)$    [As Class C IP addresses always start with 1 1 0 ]

So,required Percentage = ( 2^29 / 2^32 ) X 100

                                           =  100/8

                                           = 12.5%

Answer 2

Total ip addresses in Ipv4  (4 bytes )  = 2^32

Class A ip addresses =2^7x2^24 =2^31  so 2^31/2^32 =1/2  =50% (first bit is fixed as 0 )

Class B ip addresses =2^14x2^16=2^30  so 2^30/2^32 =1/4  =25% ( first 2 bits are fixed as 10)

Class C ip addresses =2^21x2^8 =2^29 so 2^29/2^32 =1/8  =12.5% (first 3 bits are fixed as 110 )

Rest 12.5 % left for class D and E (first 4 bits are fixed as 1110 and 1111 respectively )

Answer 3

Let, N denotes Network part and H denotes host part

CLASS C ,

Octect Format : N.N.N.H

i.e. 24 bits for Network Part and  8 bits for host part.

But out of 24 bits , first three bits are fixes which is 110,

So,  percentage (%) of the IPv4, IP address space do all class C addresses consume = (2^29/2^32)*100  %

                                                                                                                                                    = 1/8*100 %

                                                                                                                                                    = 12.5%

Answer 4

Answer will be 12.5% because leaving 110 total bits remaining = 32-3 = 29

$2^{29}/2^{32} \times100 =12.5 \   \%$