A network technician is diagnosing host networking configuration issues using command-line… — CompTIA A+ (Core 1 & Core 2)

A network technician is diagnosing host networking configuration issues using command-line diagnostic tools. Match each observed network diagnostic symptom on the left with its primary underlying configuration cause on the right.

A host network adapter receives an IPv4 address of $169.254.42.88$ with a subnet mask of $255.255.0.0$ .APIPA self-assignment caused by an unreachable or non-responsive DHCP server.
A host can communicate with local subnet devices but cannot reach remote networks, showing a Default Gateway of $0.0.0.0$ .Missing or improperly configured default gateway address.
A host can successfully ping external IP addresses ( $8.8.8.8$ ) but fails to resolve web domain names in a browser.Unresponsive or misconfigured DNS server setting.
A host displays an automatically assigned address starting with $\text{fe80::}$ on its network interface.IPv6 link-local address auto-configured for single-segment communication.

Answer

Matching pairs:

169.254.x.x

address correlates with APIPA assignment due to DHCP failure;

0.0.0.0

default gateway correlates with missing default gateway; successful IP pings with domain failure correlate with DNS misconfiguration;

\text{fe80::}

address correlates with IPv6 link-local address auto-configuration.

Each diagnostic symptom directly corresponds to a fundamental IP configuration parameter:

169.254.0.0/16

addresses represent APIPA auto-configuration during DHCP failure; an invalid

0.0.0.0

gateway prevents inter-subnet routing; successful IP pings with domain failure indicate DNS misconfiguration; and

\text{fe80::}

designates IPv6 link-local addressing.

Step-by-Step Solution

Analyze the

169.254.42.88

IP address symptom.

Identify

169.254.0.0/16

as the APIPA address block.

Operating systems automatically assign APIPA addresses when DHCP servers fail to respond to lease requests.

Analyze the

0.0.0.0

default gateway symptom.

Identify that remote network routing is missing.

Without a valid default gateway IP address, traffic cannot be routed beyond the immediate local network segment.

Analyze hostname resolution failure alongside functional numerical IP ping results.

Identify DNS resolution service failure.

Layer 3 reachability is verified by successful IP pings, which isolates the issue to hostname-to-IP translation handled by DNS.

Analyze the

\text{fe80::}

address prefix snippet.

Identify IPv6 link-local auto-configuration.

IPv6 hosts generate an

\text{fe80::/10}

link-local address for local segment communication regardless of global unicast assignment.

Key Concept

IP Addressing Parameters and Network Configuration Troubleshooting

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Step-by-Step Solution

Key Concept

Common Mistakes

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