Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
Exhibit
IP address: 10.20.30.44 Subnet mask: 255.255.255.224
Exhibit: A laptop has IP address 10.20.30.44/27. Which address is its directed broadcast for that subnet?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Distractor review
10.20.30.31
That is the broadcast of the previous /27 block.
B
Distractor review
10.20.30.32
That is the network address of this subnet.
C
Best answer
10.20.30.63
That is the directed broadcast address for 10.20.30.32/27.
D
Distractor review
10.20.30.64
That is the next subnet boundary.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is selecting the broadcast address of a different subnet or the network address instead of the directed broadcast address. For example, 10.20.30.31 is the broadcast for the previous /27 subnet (10.20.30.0/27), not the subnet containing 10.20.30.44. Similarly, 10.20.30.32 is the network address for the subnet, not a broadcast address. Confusing these addresses leads to incorrect answers. The key is to correctly identify the subnet range based on the block size and then select the highest address in that range as the directed broadcast address. Misunderstanding subnet boundaries or block sizes causes this common error.
Technical deep dive
How to think about this question
Directed broadcast addresses are special IP addresses used to send a broadcast packet to all hosts within a specific subnet. The directed broadcast address is the highest address in the subnet, where all host bits are set to 1. For a subnet with a /27 mask, which corresponds to 255.255.255.224, the block size is 32 addresses. This means each subnet contains 32 IP addresses, including the network and broadcast addresses. To find the directed broadcast address for a given IP and subnet mask, first identify the subnet range by calculating the network address. For 10.20.30.44/27, the network address is 10.20.30.32 because 44 falls within the 32–63 range. The directed broadcast address is then the last address in this range, 10.20.30.63, where all host bits are set to 1. Cisco devices use this address to forward broadcast packets to all hosts in that subnet. A common exam trap is confusing the directed broadcast address with the network address or the broadcast address of a different subnet. For example, 10.20.30.31 is the broadcast for the previous subnet (10.20.30.0/27), not the current one. Understanding subnet boundaries and block sizes is critical to avoid this mistake. In practical networking, directed broadcasts can be used for network-wide announcements but are often disabled on routers to prevent broadcast amplification attacks.
KKey Concepts to Remember
- A /27 subnet mask corresponds to 255.255.255.224 and creates subnets with 32 IP addresses each, including network and broadcast addresses.
- The directed broadcast address is the highest IP address in a subnet, where all host bits are set to 1, used to broadcast to all hosts in that subnet.
- To find the directed broadcast address, first calculate the network address by zeroing host bits, then add the block size minus one to get the broadcast address.
- The host IP 10.20.30.44/27 belongs to the subnet 10.20.30.32/27, which ranges from 10.20.30.32 to 10.20.30.63, making 10.20.30.63 the directed broadcast address.
- Confusing the directed broadcast address with the network address or broadcast address of adjacent subnets is a common exam mistake.
- Cisco routers use directed broadcast addresses to forward broadcast packets within a subnet, but these are often disabled for security reasons.
- Subnetting calculations require understanding block sizes and subnet boundaries to correctly identify network and broadcast addresses.
- Directed broadcast addresses are critical in network communication and troubleshooting, especially when dealing with subnet-specific broadcasts.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?
FAQ
Questions learners often ask
What does this 200-301 question test?
A /27 subnet mask corresponds to 255.255.255.224 and creates subnets with 32 IP addresses each, including network and broadcast addresses.
What is the correct answer to this question?
The correct answer is: 10.20.30.63 — A /27 gives a block size of 32 addresses. The host 10.20.30.44 falls in the 10.20.30.32 to 10.20.30.63 subnet, so the broadcast address is 10.20.30.63.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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