If the user cannot communicate with 192.168.10.1, they might be on a different subnet. Changing the subnet mask to 255.255.255.0 ensures the user and the file server are in the same subnet.
Breakdown of Options:
A: Changing the IPv4 address to 192.168.10.1 - This would conflict with the server's IP.
B: Changing the subnet mask to 255.255.255.0 - # Correct answer. Ensures both the user and the server are on the same subnet.
C: Changing the DNS servers - DNS does not affect local network connectivity.
D: Changing the physical address - The MAC address does not impact subnet communication.
Reference:
CompTIA Network+ (N10-009) Official Study Guide - Domain 2.4: Explain subnetting and addressing concepts.