• Last Updated : 17 Jul, 2020

 Question 1
In the IPv4 addressing format, the number of networks allowed under Class C addresses is
 A 2 14 B 2 7 C 2 21 D 2 24
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Question 1 Explanation:
In class C, 8 bits are reserved for Host Id and 24 bits are reserved for Network Id. Out of these 24 Network Id bits, the leading 3 bits are fixed as 110. So remaining 21 bits can be used for different networks. See this for more details.
 Question 2
In the IPv4 addressing format, the number of networks allowed under Class C addresses is
 A 2 14 B 2 7 C 2 21 D 2 24
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Question 2 Explanation:
In class C, 8 bits are reserved for Host Id and 24 bits are reserved for Network Id. Out of these 24 Network Id bits, the leading 3 bits are fixed as 110. So remaining 21 bits can be used for different networks. See this for more details.
 Question 3
A n Internet Service Provider (ISP) has the following chunk of CIDR-based IP addresses available with it: 245.248.128.0/20. The ISP wants to give half of this chunk of addresses to Organization A, and a quarter to Organization B, while retaining the remaining with itself. Which of the following is a valid allocation of addresses to A and B?
 A 245.248.136.0/21 and 245.248.128.0/22 B 245.248.128.0/21 and 245.248.128.0/22 C 245.248.132.0/22 and 245.248.132.0/21 D 245.248.136.0/24 and 245.248.132.0/21
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Question 3 Explanation:
 Question 4
Suppose computers A and B have IP addresses 10.105.1.113 and 10.105.1.91 respectively and they both use the same netmask N. Which of the values of N given below should not be used if A and B should belong to the same network?
 A 255.255.255.0 B 255.255.255.128 C 255.255.255.192 D 255.255.255.224
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Question 4 Explanation:
 Question 5
If a class B network on the Internet has a subnet mask of 255.255.248.0, what is the maximum number of hosts per subnet?
 A 1022 B 1023 C 2046 D 2047
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Question 5 Explanation:
 Question 6
The address of a class B host is to be split into subnets with a 6-bit subnet number. What is the maximum number of subnets and the maximum number of hosts in each subnet?
 A 62 subnets and 262142 hosts. B 64 subnets and 262142 hosts. C 62 subnets and 1022 hosts. D 64 subnets and 1024 hosts.
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Question 6 Explanation:
 Question 7
The subnet mask for a particular network is 255.255.31.0. Which of the following pairs of IP addresses could belong to this network?
 A 172.57.88.62 and 172.56.87.233 B 10.35.28.2 and 10.35.29.4 C 191.203.31.87 and 191.234.31.88 D 128.8.129.43 and 128.8.161.55
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Question 7 Explanation:
Background required - Subnetting and SubNet Mask Answer - D Explanation - Suppose we have a host A with IP Address IPA and Subnet mask of the subnet of which A is a part is Ms. Now when A wants to send packet to a host B with an IP address say IPB, then A will first AND the subnet-Mask Ms with IPA to find out the subnet-id IDN of the subnet in order to identify whether IPB belongs to the same network. Now if B also belongs to the same network, then IPB BITWISE-AND Ms must be equal to IDN which A has calculated. If IPA and IPB belongs to same network, we must have
```	IPA BITWISE-AND Ms == IPBBITWISE-AND Ms
```
Out of the 4 options, only option D matches.
```128.8.129.43 BITWISE-AND 255.255.31.0 = 128.8.1.0
128.8.161.55 BITWISE-AND 255.255.31.0 = 128.8.1.0
```
You can check rest of the options. This explanation has been provided by Pranjul Ahuja.
 Question 8
Consider the following routing table at an IP router For each IP address in Group-I identify the correct choice of the next hop from Group-II using the entries from the routing table above.
```   List-I               List-II
A. 128.96.171.92     1. Interface 0
B. 128.96.167.151    2. Interface 1
C. 128.96.163.121    3. R2
D. 128.96.165.121    4. R3
5. R4
Codes:
A B C D
(a)  1 3 5 4
(b)  1 4 2 5
(c)  2 3 4 5
(d)  2 3 5 4```
 A a B b C c D d
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Question 8 Explanation:
The next hop is decide according to the longest prefix matching.  Refer following link for details. https://www.youtube.com/watch?v=PSC5omE3pX8&list=PLkHsKoi6eZnzJl1qTzmvBwTxrSJW4D2Jj&index=32
 Question 9
Which of the following IP address can be used in WAN?
 A 10.0.0.1 B 172.16.0.10 C 15.1.5.6 D None
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Question 9 Explanation:
10.0.0.1  and 172.16.0.10 are private IP address. Thus cannot be used in WAN.  15.1.5.6 is a public IP address.
 Question 10
Which of the following can be used as both Source and Destination IP?
 A 198.168.1.255 B 10.0.0.1 C 127.0.0.1 D 255.255.255.255