Convert Masks, Drill 1: Answers
Today’s post lists the answers from Convert Masks, Drill 1. If you have questions on any of the 6 problems, post away. Some related posts:
- Original problem blog post
- How to: ICND1 Official Cert Guide (Chapter 14 in Edition 3, Pub 2011)
- How to: Overview post in this blog
Answers to Convert Masks, Drill 1:
Problem 4 lists a binary number that is illegal as a mask. All binary versions of subnet masks must have an unbroken string of binary 1’s, and then the rest binary 0’s. It cannot interleave 1’s and 0’s. The rest were legal.
All the original problems are shown in bold; the not bolded parts show the answers.
Table 2: Convert Masks, Drill 1, Answers
Binary | Prefix | DDN | |
1 | 11111111 11111111 11111100 00000000 | /22 | 255.255.252.0 |
2 | 11111111 11111000 00000000 00000000 | /13 | 255.248.0.0 |
3 | 11111111 11111111 11111111 11100000 | /27 | 255.255.255.224 |
4 | 11111111 11111111 11111100 11110000 | ||
5 | 11111111 11111111 11111110 00000000 | /23 | 255.255.254.0 |
6 | 11111111 11111100 00000000 00000000 | /14 | 255.252.0.0 |
Hi, there’s no answer to #4 above, only a question.
Hi Bill,
Problem 4 has the answer in the text above the table. It’s an illegal value, so there’s no correct value to list in the table. Sorry it was difficult to find…
Wendell