Finding the broadcast address — Aptitude Question
Finding the broadcast address: A host is configured with the address 192.168.10.75 and the subnet mask… Answer and worked solution on CodeKairo.
- Topic: OS, DBMS & Networks
- Section: Programming MCQs
- Difficulty: Hard
- Time target: 150 seconds
Question
A host is configured with the address 192.168.10.75 and the subnet mask 255.255.255.192. What is the broadcast address of its subnet?
Options
- 192.168.10.63
- 192.168.10.64
- 192.168.10.127
- 192.168.10.255
Show the answer and the worked solution
Correct answer: C. 192.168.10.127
Worked solution
- The mask 255.255.255.192 is a /26, so subnets step through the last octet in blocks of 256 − 192 = 64.
- The subnet boundaries are therefore .0, .64, .128 and .192, and 75 falls inside the block that starts at .64.
- That block ends one address below the next boundary at .128, so the broadcast address is 192.168.10.127 and the usable range is .65 to .126.
Answer: 192.168.10.127.
The idea
The block-size trick — 256 minus the interesting octet of the mask — converts every subnetting question into simple counting, with no binary conversion needed.
Shortcut. A broadcast address has all host bits set, so it must be odd, which rules out .64; .63 belongs to the block before 75, and .255 would need a /24 mask.
Common trap. "192.168.10.255" applies the default /24 broadcast and ignores the .192 mask that cuts the octet into blocks of 64.