CompTIA Server+ (SK0-005)Server AdministrationHard
A server administrator is troubleshooting network connectivity issues on a newly deployed server. The server is configured with a static IP address, but it cannot reach other devices on the same subnet. Pinging the default gateway also fails. The administrator suspects a misconfigured subnet mask. The server's IP is 192.168.1.10/24, and the gateway is 192.168.1.1. If the subnet mask was accidentally set to 255.255.0.0 instead of 255.255.255.0, what would be the impact on communication within the 192.168.1.0/24 network?
- AThe server would not be able to obtain an IP address, preventing any communication.
- BThe server would correctly identify its local subnet but incorrectly route all traffic through the gateway.
- CThe server would treat all 192.168.x.x addresses as being on its local subnet, causing direct communication attempts to fail.
- DThe server would only be able to communicate with devices outside its local network.
Show answer & explanationAnswer & explanation
Correct answer: C. The server would treat all 192.168.x.x addresses as being on its local subnet, causing direct communication attempts to fail.
A subnet mask of 255.255.0.0 (/16) would make the server believe that all 192.168.x.x addresses are on its local subnet. When trying to reach 192.168.1.1 (the gateway), it would attempt direct ARP resolution instead of routing through the gateway, which would fail if the gateway truly resides on a /24 network.
Why the other options are wrong
- A. The server has a static IP; obtaining an IP address is not the issue, but rather how it perceives its local network boundary.
- B. An incorrect subnet mask would prevent the server from correctly identifying its local subnet, leading to incorrect routing decisions.
- D. This is incorrect; a misconfigured subnet mask would hinder local communication, not enable external-only communication.
Subnet Mask Impact
A subnet mask defines the boundary between the network portion and the host portion of an IP address. An incorrect subnet mask can cause local and remote communication failures by misidentifying network boundaries.
- Determines local vs. remote addresses
- Incorrect mask leads to incorrect routing
- A /16 mask on a /24 network makes the local network appear larger
Memory trick: Subnet masks: the invisible fence of your network!