A network technician is troubleshooting an issue where a client workstation (10.1.10.5/24)… — CompTIA Network+

A network technician is troubleshooting an issue where a client workstation ( $10.1.10.5/24$ ) cannot access a web application hosted on a remote server ( $172.16.20.50/24$ ). Place the following diagnostic and remediation steps in the correct chronological order, adhering to standard CompTIA troubleshooting methodology from initial local verification through resolution.

1Ping the local default gateway ( $10.1.10.1$ ) from the client workstation to confirm local Layer 3 connectivity.
2Execute a `traceroute 172.16.20.50` command from the workstation to identify the specific hop where packet forwarding stops.
3Access the router where traffic halted and execute `show ip route` to check if a valid route to $172.16.20.0/24$ exists.
4Inspect interface Access Control Lists using `show ip access-lists` on the router to verify if traffic is blocked by an explicit or implicit deny rule.
5Modify the ACL to permit traffic from $10.1.10.0/24$ to $172.16.20.50/24$ and test end-to-end web access to verify full resolution.

Cevap

The correct troubleshooting sequence is: 1) Ping the local default gateway, 2) Execute traceroute to locate the failing hop, 3) Check the routing table on the failing router, 4) Inspect interface ACLs for filtering rules, and 5) Modify the ACL and perform end-to-end verification.

The correct order follows the standard bottom-up/top-down structured troubleshooting approach: first verify local default gateway connectivity, then use path detection (traceroute) to find the failure point, inspect the routing table on that router, check for restrictive ACL filtering rules, and finally apply the fix and verify end-to-end reachability.

Adım Adım Çözüm

Test local subnet gateway connectivity using ping.

Confirms client host network stack and local router interface are operational.

Always test closest local dependencies before diagnosing remote infrastructure.

Perform path discovery using traceroute to destination IP 172.16.20.50.

Pinpoints the exact intermediate router hop where traffic ceases to forward.

Narrows down the scope of network devices requiring inspection.

Examine the IP routing table on the failing router using `show ip route`.

Verifies whether a valid next-hop or exit interface route exists for 172.16.20.0/24.

Determines if the issue is layer 3 route reachability or packet filtering.

Review active ACL entries applied to inbound/outbound interfaces using `show ip access-lists`.

Identifies if traffic matching 10.1.10.5 to 172.16.20.50 is caught by a deny rule or implicit deny.

If routing exists, access control filtering is the next logical root cause to inspect.

Apply correct ACL permit statement and verify application connectivity.

Restores full end-to-end functionality and verifies the fix.

Remediates the root cause and verifies complete solution functionality.

Anahtar Kavram

Structured network troubleshooting methodology for routing, default gateways, and ACL filtering.

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