🏠 Home Networking
10 분 소요
Network Troubleshooting Toolkit
Essential commands and techniques for diagnosing home network problems including DNS failures, slow speeds, connectivity drops, and Wi-Fi issues.
The Troubleshooting Process
When something is not working, follow this systematic approach:
- Physical layer — Is the cable plugged in? Is Wi-Fi connected?
- Local connectivity — Can you reach your router?
- DNS resolution — Can you resolve domain names?
- Internet connectivity — Can you reach external IPs?
- Application layer — Is the specific service down?
Essential Commands
ping — Test Reachability
# Can you reach your router?
ping 192.168.1.1
# Can you reach the internet by IP? (bypasses DNS)
ping 8.8.8.8
# Can you reach by name? (tests DNS)
ping google.com
# If IP works but name fails → DNS problem
# If neither works → connectivity problem
traceroute — Find Where Traffic Stops
# macOS/Linux
traceroute google.com
# Windows
tracert google.com
# Look for:
# * * * = hop not responding (may be normal — ICMP filtered)
# High latency at a specific hop = congestion point
# Route stopping = connectivity break at that hop
nslookup / dig — DNS Diagnostics
# Basic DNS lookup
nslookup example.com
# Query a specific DNS server
nslookup example.com 8.8.8.8
# Detailed DNS query (Linux/macOS)
dig example.com A +trace
# If your ISP DNS fails but 8.8.8.8 works:
# → Change DNS servers in router settings
netstat / ss — Check Connections
# Show all listening ports (Linux)
ss -tlnp
# Show active connections (macOS)
netstat -an | grep ESTABLISHED
# Check if a service is running on expected port
ss -tlnp | grep :80
Common Problems & Solutions
| Symptom | Likely Cause | Fix |
|---|---|---|
| No connectivity | DHCP failure | Release/renew IP or set static |
| Can ping IP, not names | DNS failure | Change DNS to 8.8.8.8 or 1.1.1.1 |
| Intermittent drops | Wi-Fi interference | Change channel, move router |
| Slow speeds | Bandwidth congestion | Check for background downloads, QoS |
| One device, no issue on others | Device config | Check IP, DNS, proxy settings |
Wi-Fi Specific Diagnostics
# macOS: Scan nearby networks and channels
/System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport -s
# Check which channel your router uses and if neighbors overlap
# Best channels for 2.4 GHz: 1, 6, or 11 (non-overlapping)
# 5 GHz: More channels, less interference
When to Restart
If systematic troubleshooting does not identify the issue, the "restart cascade" often helps:
- Restart the device having problems.
- Restart the router (wait 30 seconds, then power on).
- Restart the modem/ONT (wait 60 seconds).
- If ISP-side, contact your provider with traceroute results.