CCENT/CCNA ICND1 100-101 Official Cert Guide

Practice Problem 1

Table I-2 Practice Problem 1: First Two Steps

For Problem 1, at Step 3, the shortest mask is /21, so the initial mask will be one smaller, or /20. Finding the correct answer requires four passes through calculating a new subnet ID and mask, with the final answer shown in Table I-3.

Table I-3 Practice Problem 1: Multiple Passes Through Step 4 (Correct Answer Highlighted)

The best summary route will use subnet ID 10.100.128.0, mask /17.