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Difficulty: Very hardUtilizing Command-Line Network Troubleshooting Utilities

A network administrator is troubleshooting an issue where a workstation cannot access a critical web database service hosted at `db01.corp.internal` on TCP port 8443 in a remote subnet. Following standard network troubleshooting methodology to systematically isolate the issue from the local network layer up through path routing, domain name resolution, and transport socket state, in what logical sequence should the administrator execute the command-line network utilities?

  1. 1Execute `ipconfig /all` to verify local host IP address, subnet mask, default gateway, and DNS server configuration.
  2. 2Execute `ping 192.168.1.1` (the default gateway address) to test ICMP reachability across the local segment.
  3. 3Execute `tracert -d 10.250.32.50` to map Layer 3 hop-by-hop path reachability to the destination IP address without resolving hostnames.
  4. 4Execute `nslookup db01.corp.internal 10.1.1.5` to test direct name resolution against the authoritative internal DNS server.
  5. 5Execute `netstat -ano | findstr :8443` to inspect TCP socket states and verify session establishment on the target application port.

Answer

The correct logical execution sequence begins with local adapter configuration verification (`ipconfig /all`), followed by local gateway ICMP reachability (`ping 192.168.1.1`), then path routing analysis via destination IP (`tracert -d 10.250.32.50`), explicit DNS query resolution (`nslookup db01.corp.internal 10.1.1.5`), and concludes with transport layer socket state inspection (`netstat -ano | findstr :8443`).
Structured network troubleshooting mandates moving logically from the local host configuration outward through the network infrastructure up to higher-layer application services. Step 1 validates local interface settings (`ipconfig /all`). Step 2 tests local LAN/gateway reachability (`ping gateway`). Step 3 traces the Layer 3 path using an IP address to bypass DNS dependencies (`tracert -d IP`). Step 4 confirms domain name mapping via DNS (`nslookup FQDN DNS_IP`). Step 5 evaluates specific Layer 4 TCP port handshake and connection states (`netstat -ano`).

Step-by-Step Solution

1
Verify local TCP/IP protocol stack and interface settings using `ipconfig /all`.
Confirms valid IP addressing, subnet mask, default gateway IP, and primary DNS server IP.
Root cause isolation must start at Layer 1-3 on the local endpoint before sending traffic across the network.
2
Test local link and default gateway communication using `ping 192.168.1.1`.
Determines whether local Layer 2 switching and local Layer 3 router interface communication is operational.
If the local gateway is unreachable, traffic cannot be routed to remote subnets.
3
Trace the Layer 3 routing path using IP address targeting with `tracert -d 10.250.32.50`.
Identifies the exact WAN/VPN router hop where packet forwarding fails or experiences severe latency.
Using `-d` bypasses DNS lookups during path tracing, preventing DNS failures from masking path routing failures.
4
Query DNS service directly using `nslookup db01.corp.internal 10.1.1.5`.
Verifies whether the internal DNS server returns the accurate A/AAAA resource record for the target FQDN.
Isolates application reachability failures caused by incorrect DNS records or DNS server unresponsiveness.
5
Analyze transport session establishment using `netstat -ano | findstr :8443`.
Displays active TCP connection states (e.g., SYN_SENT, ESTABLISHED, TIME_WAIT) for the target port.
Determines whether Layer 4 TCP three-way handshake succeeds or is blocked by access control lists (ACLs) or firewalls.

Key Concept

Bottom-Up and Layered CLI Diagnostic Workflow for Network Troubleshooting
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Topics

Utilizing Command-Line Network Troubleshooting Utilities

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