CCST IP Addressing & Subnetting 3 — Questions and Answers
Question 1: A company needs 5 subnets with at least 25 hosts each from 192.168.1.0/24. Which subnet mask satisfies this?
- 255.255.255.224 (/27) (Correct answer)
- 255.255.255.240 (/28)
- 255.255.255.192 (/26)
- 255.255.255.128 (/25)
Correct answer: 255.255.255.224 (/27)
/27 provides 30 usable hosts per subnet and allows 8 subnets from a /24, meeting both requirements.
Question 2: What is the purpose of the loopback address 127.0.0.1?
- To test the local TCP/IP stack without sending traffic on the network (Correct answer)
- To assign a temporary address when DHCP fails
- To identify the default gateway
- To communicate with all hosts on the local subnet
Correct answer: To test the local TCP/IP stack without sending traffic on the network
127.0.0.1 is the loopback address used to test that the local IP stack is functioning correctly.
Question 3: Which subnet does the host 192.168.5.200/28 belong to?
- 192.168.5.192 (Correct answer)
- 192.168.5.176
- 192.168.5.208
- 192.168.5.224
Correct answer: 192.168.5.192
/28 uses 16-address blocks; 192 is the nearest multiple of 16 ≤ 200, so the network is 192.168.5.192.
Question 4: In IPv4 subnetting, what does the term 'magic number' refer to?
- The block size used to calculate subnet boundaries (Correct answer)
- The number of usable hosts in a subnet
- The number of bits borrowed for subnetting
- The value of the subnet mask in decimal
Correct answer: The block size used to calculate subnet boundaries
The magic number (256 minus the interesting octet of the subnet mask) gives the block size for calculating subnet boundaries.
Question 5: How many subnets are created when you borrow 3 bits from the host portion of a Class C network?
- 8 (Correct answer)
- 6
- 4
- 16
Correct answer: 8
Borrowing 3 bits creates 2^3 = 8 subnets.
Question 6: What is the network address of 10.10.10.130/25?
- 10.10.10.128 (Correct answer)
- 10.10.10.0
- 10.10.10.64
- 10.10.10.192
Correct answer: 10.10.10.128
/25 splits the last octet into two halves: .0–.127 and .128–.255; since .130 falls in the second half, the network is 10.10.10.128.
Question 7: Which address range is reserved for IPv4 multicast traffic?
- 224.0.0.0–239.255.255.255 (Correct answer)
- 240.0.0.0–255.255.255.255
- 192.168.0.0–192.168.255.255
- 169.254.0.0–169.254.255.255
Correct answer: 224.0.0.0–239.255.255.255
Class D addresses, ranging from 224.0.0.0 to 239.255.255.255, are reserved for multicast group communication.
CCST IP Addressing & Subnetting 3
A company needs 5 subnets with at least 25 hosts each from 192.168.1.0/24.
Which subnet mask satisfies this?