The issue is that more students have arrived on campus, meaning the available IP addresses are exhausted. To fix this, the administrator should increase the DHCP scope size to allow more devices to obtain IP addresses.
Breakdown of Options:
A). Enable IP helper - IP helper is used to forward DHCP requests across different subnets. However, the problem here is that the DHCP scope is full, not that requests are not reaching the server.
B). Change the subnet mask - The subnet mask determines the number of available hosts, but changing it without increasing the IP pool does not help.
C). Increase the scope size - Correct answer. Expanding the DHCP scope provides more IP addresses for assignment.
D). Add address exclusions - Exclusions reserve IP addresses, which would further reduce available addresses instead of solving the issue.
Reference:
CompTIA Network+ (N10-009) Official Study Guide - Domain 2.4: Compare and contrast IP addressing schemes.
RFC 2131: Dynamic Host Configuration Protocol (DHCP)