IPV4

Question

Which of the following IP address requires approval from ISP for obtaining them?

(i) 172.19.24.24   (ii) 13.13.13.13

(iii) 192.168.20.1  (iv) 192.167.0.1

1. Only (i) and (iii)
2. Only (i) and (iv)
3. Only (ii) and (iii)
4. Only (ii) and (iv)

why are these address special that they have to be approved from ISP?

Comments

Some IP addresses are reserved for private use and some for public. So, public ones must be obtained from ISP.

Answer 1

1st and 3rd IP address are private ip address of class B and class C respectively.

Private IP range:

class C    192.168.0.0 - 192.168.255.255 (65,536 IP addresses)
class B    172.16.0.0 - 172.31.255.255 (1,048,576 IP addresses)
class A    10.0.0.0 - 10.255.255.255 (16,777,216 IP addresses)

these can be used by intra-network, ip allocation by your home wifi router to your laptop, mobiles etc (class c, thats why most of the router admin panel can be accessed at class c address that is 192.168.x.x by default)  as a NAT.

2nd and 4th IP does not belong to private IP thus they are with ISP.