IP Subnetting

Subnetting Resources

Books

Find all of our books on the Books page.

Video Training

https://www.101labs.net – Training course for 101 Labs – IP Subnetting

https://www.howtonetwork.com – Video training course matching this book (under TCP/IP)

RFCs

RFC 1918 – Address allocation for private internets RFC 1219 – On the assignment of subnet numbers RFC 950 – Internet standard subnetting procedure RFC 940 – Toward an internet standard scheme for subnetting RFC 932 – Subnetwork addressing scheme RFC 917 – Internet subnets

The Subnetting Cheat Chart

 Bits1286432168421
Subnets         
128         
192         
224         
240         
248         
252         
254         
255         
Powers of 2SubnetsHosts – 2       
2         
4         
8         
16         
32         
64         
128         
256         
512         
1024         
2048         
4096         
8192         
16384         

IP Subnetting – Exam 3

1. Which of the following addresses is not routable on the internet?

Question 1 of 50

2. Which of the following addresses range is used by Automatic Private IP Addressing (APIPA)?

Question 2 of 50

3. The network address of 172.29.0.0/22 provides how many subnets and hosts?

Question 3 of 50

4. Which CIDR notation is recommended to use on the point-to-point link?

Question 4 of 50

5. What is the highest usable address on the 192.168.252.128/25 network?

Question 5 of 50

6. What represents the decimal equivalence of 10101000?

Question 6 of 50

7. You have been assigned a 192.168.252.0 network. The requirement is to have a minimum of 7 subnets, each containing a minimum of 25 hosts. Which network mask would you use?

Question 7 of 50

8. The subnet mask is used to identify an IP address as either private or public

Question 8 of 50

9. Which of the following statements are true about subnet mask?

Question 9 of 50

10. What is the correct CIDR notation for an IP address of 10.220.12.131 with a subnet mask of 255.255.248.0?

Question 10 of 50

11. Which of the following is a next usable IP address after 10.220.32.254, if the subnet mask is 255.255.224.0?

Question 11 of 50

12. When dividing the Class C network 192.168.10.0/25 into 4 separate networks, what is the range of usable host IP addresses for the last subnet?

Question 12 of 50

13. Which statements are true about Variable Length Subnet Mask (VLSM)?

Question 13 of 50

14. Refer to the diagram below

Which statements describe the addressing scheme that is in use in the network?

Question 14 of 50

15. You must assign a static IP address to a Windows server machine in a network. From the subnet 192.168.200.64/28, the default gateway would be the first usable IP address while the windows server is assigned the last usable IP address. Which of the following you should enter into the Windows server IP settings?

Question 15 of 50

16. You have been asked to design an IP addressing scheme for a company. The requirement is to have 4 subnets and a maximum of 60 host addresses per subnet. Working with only one Class C address, which of the following subnet mask will you use?

Question 16 of 50

17. You are subnetting 172.16.20.0/22 into a /28 mask, and how many usable host addresses will there be per subnet?

Question 17 of 50

18. Which of the following notation types is used in 192.168.10.2/24 IP address?

Question 18 of 50

19. Your company is opening three branch offices. Each branch office would have 10 computers and future expansion is expected to have around 20 computers. Which subnet mask will meet this requirement?

Question 19 of 50

20. Class C addresses range from 192.0.0.0 through 223.255.255.255 and use a default subnet mask of 255.255.255.0. Which of the following is the routable public class C address?

Question 20 of 50

21. What would be the default subnet mask of an 11.21.1.11 IP address?

Question 21 of 50

22. For a point-to-point link, the smallest valid subnet mask can be generated by which CIDR notation?

Question 22 of 50

23. You have been given an IP subnet 192.168.100.0/24, you want to isolate different company's departments. Which of the following is the best practice to follow?

Question 23 of 50

24. Computers on the same network will have the different network ID portion of an IP address, whereas the host ID portion will be same

Question 24 of 50

25. Identify the network ID portion of the 10.230.100.3/16 IP address

Question 25 of 50

26. Which of the following are valid subnet masks, represented in their binary form?

Question 26 of 50

27. Match the IP address with its class
1.0.0.127
Class A

Unselect

Class C

Unselect

Class D

Unselect

Class B

Unselect

129.100.200.254
Class A

Unselect

Class C

Unselect

Class D

Unselect

Class B

Unselect

221.100.20.1
Class A

Unselect

Class C

Unselect

Class D

Unselect

Class B

Unselect

230.100.100.101
Class A

Unselect

Class C

Unselect

Class D

Unselect

Class B

Unselect

Question 27 of 50

28. In Class A addresses range, which of the following subnet masks provides the highest number of hosts IP addresses?

Question 28 of 50

29. Which of the following is the binary representation of an IP 10.15.9.1?

Question 29 of 50

30. If a computer is not able to get an IP from a DHCP server, which of the following process will the client use to generate an address for itself?

Question 30 of 50

31. Which of the following is the decimal representation of an address 11000000.10101000.00001010.00000001?

Question 31 of 50

32. Which of the following is the broadcast address of 192.168.10.64/28 subnet?

Question 32 of 50

33. Classful addressing uses fixed network IDs based on the first octet of the IP address

Question 33 of 50

34. Which IPv4 network class address contains a first octet in the range of 192-223?

Question 34 of 50

35. Which of the following statements are true about IP addresses?

Question 35 of 50

36. Which of the following are not class C IP addresses?

Question 36 of 50

37. Why a subnet mask of 255.255.255.252 will allow for only 2 usable IP addresses?

Question 37 of 50

38. If there are 7 bits available to address hosts in a network, how many usable IP addresses can be accommodated?

Question 38 of 50

39. In your company, the requirement is to have at least 2 subnets with 500 hosts per subnet. Which of the following subnet masks will satisfy this requirement?

Question 39 of 50

40. Find the next valid subnets after 192.168.254.96/27. Also, match any that are invalid
First
192.168.254.224/27

Unselect

192.168.254.160/27

Unselect

192.168.254.33/27

Unselect

192.168.254.128/27

Unselect

Second
192.168.254.224/27

Unselect

192.168.254.160/27

Unselect

192.168.254.33/27

Unselect

192.168.254.128/27

Unselect

Fourth
192.168.254.224/27

Unselect

192.168.254.160/27

Unselect

192.168.254.33/27

Unselect

192.168.254.128/27

Unselect

Invalid
192.168.254.224/27

Unselect

192.168.254.160/27

Unselect

192.168.254.33/27

Unselect

192.168.254.128/27

Unselect

Question 40 of 50

41. Match the address for a /21 network to its usage
Network ID
10.230.24.0/21

Unselect

10.231.31.256/21

Unselect

10.230.31.255/21

Unselect

10.230.39.254/21

Unselect

Broadcast ID
10.230.24.0/21

Unselect

10.231.31.256/21

Unselect

10.230.31.255/21

Unselect

10.230.39.254/21

Unselect

Valid Host
10.230.24.0/21

Unselect

10.231.31.256/21

Unselect

10.230.31.255/21

Unselect

10.230.39.254/21

Unselect

Invalid Host
10.230.24.0/21

Unselect

10.231.31.256/21

Unselect

10.230.31.255/21

Unselect

10.230.39.254/21

Unselect

Question 41 of 50

42. How many subnets can you create if you have been assigned 10.31.255.128/19?

Question 42 of 50

43. The IP address 192.168.200.171/27 and 192.168.200.190/27 belongs to which of the following subnets?

Question 43 of 50

44. Public IP addresses are provided for internal communication within a company's network

Question 44 of 50

45. Which of the following statements are true about the IPv4 addressing scheme?

Question 45 of 50

46. When subnetting a class B network, the subnet mask begins changing in the third octet

Question 46 of 50

47. How many networks are created if a subnet mask is changed from 255.252.0.0 to 255.255.252.0?

Question 47 of 50

48. How many bits are in the host ID of an IP address after subnetting a class A network into 4 subnets?

Question 48 of 50

49. The ANDing of an IP address to its subnet mask results in which of the following?

Question 49 of 50

50. In subnetting, neither the host bits nor the network bits can be reassigned

Question 50 of 50


 

Public vs. Private IP Addresses: Unraveling the Mystery

You may already know that there is a finite number of IPv4 addresses available on the internet. This is mostly because our current IP addressing system was created back in 1980 when computers were very large and expensive and only owned by corporations or university’s computer engineering departments.

It was anticipated back then that very few IP addresses would ever be needed, so a 32-bit addressing scheme was considered more than enough!

Of course, there was an explosion of computer users, and an alternative was needed. That alternative is IPv6, but it would take a few years to plan and implement, so in the meantime, ways of preserving IP addresses had to be developed.

One such method was created by a policy document called RFC 1918. An RFC is a Request For Comment and is a technical document that describes the specifications, protocols, procedures, or best practices related to the internet and computer networking. They are used to propose new protocols or services we can use on the internet for security, addressing, sharing files, synchronizing clocks, and more.

Read More

What is IP Subnetting?

In simple terms, IP subnetting breaks down your network into smaller, easy-to-manage chunks. It’s just like cutting a cake into pieces so that it’s available to more people.

If you cut the cake, instead of one cake for one person, you get slices. The more slices you cut, the more people get a piece of the cake, but the slices they get are smaller.

ip subnetting

Image copyright – amyshiddenpantry.com

Depending on how we cut the cake in IP addressing terms, we break the network into smaller and smaller pieces. One huge piece to one person would be a waste, so we have to determine a balance of how many slices we cut against how many people need some cake vs the size of the cake we paid for of course.

Let’s look at why we would do this.

Read More

What Are IP Address Classes?

IP address classes were an early method of organizing IP addresses within the Internet Protocol Version 4 (IPv4) system. They were designed to divide the available IP address space into different network sizes, making it easier to allocate addresses efficiently.

Although we no longer use the original IP address classes to allocate network addresses, we do still refer to IP addresses by their Class letters. You may well also be tested on classes in your IT exams so it’s worth knowing.

Read More