A network administrator receives a report that a newly assigned workstation on VLAN 25 (10… — CompTIA Network+

A network administrator receives a report that a newly assigned workstation on VLAN 25 ( $10.25.0.0/24$ ) cannot access remote intranet services. Upon inspecting the workstation, the administrator observes an auto-configured IPv4 address of $169.254.42.10$ . Place the following diagnostic and remediation steps in the correct logical sequence to systematically troubleshoot and resolve this DHCP relay issue from client verification to final resolution.

1Run `ipconfig /all` on the local workstation to confirm link status and verify the presence of an APIPA address ( $169.254.x.x$ ).
2Temporarily assign a valid static IP ( $10.25.0.99/24$ ) to the workstation and ping the default gateway ( $10.25.0.1$ ) to verify local VLAN connectivity.
3Inspect the Layer 3 switch or router interface configuration for VLAN 25 to verify the `ip helper-address` directive pointing to the centralized DHCP server.
4Verify on the DHCP server that a scope for $10.25.0.0/24$ exists, is activated, and has available addresses in its pool.
5Reconfigure the workstation to receive an IP automatically and execute `ipconfig /release` followed by `ipconfig /renew` to confirm lease acquisition.

Cevap

The correct logical sequence begins with client-side verification (`ipconfig /all`), followed by testing local subnet connectivity using a static IP, checking the router's DHCP relay (`ip helper-address`) configuration, confirming DHCP server scope availability for VLAN 25, and finally releasing and renewing the client's lease.

Following the structured troubleshooting methodology, an administrator must first verify client symptoms (APIPA confirmation), isolate local physical and VLAN connectivity using a temporary static IP, verify that the Layer 3 boundary device is properly configured with a DHCP relay agent (`ip helper-address`), ensure the remote DHCP server has an active scope for that subnet, and finally test dynamic acquisition on the client.

Adım Adım Çözüm

Confirm client symptom and network stack state

Identify that the client holds an APIPA address (

169.254.42.10

), proving DHCP DISCOVER messages failed to receive an OFFER.

CompTIA troubleshooting methodology mandates verifying the problem and gathering initial symptoms on the affected client first.

Isolate local Layer 2/3 network path

Confirming ping to

10.25.0.1

works under a temporary static IP proves local cabling, NIC, and switch VLAN configuration are functional.

Eliminates basic physical and local link issues before troubleshooting higher-level services across subnets.

Audit gateway DHCP relay configuration

Identify if `ip helper-address` is missing or pointing to an incorrect IP on the gateway interface for VLAN 25.

DHCP broadcasts cannot cross routers without a relay agent forwarding unicast requests to the DHCP server.

Audit central DHCP server scope state

Ensure the server scope for

10.25.0.0/24

is active, not scope-exhausted, and configured with correct options.

Even with a working relay agent, an unactivated or exhausted scope prevents IP assignment.

Verify resolution on client

Client successfully receives an IP address in the

10.25.0.0/24

range via dynamic lease renewal.

Confirms full end-to-end functionality of the DHCP process.

Anahtar Kavram

DHCP Relay and APIPA Troubleshooting Methodology across Subnets

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Cevap

Adım Adım Çözüm

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