Network Debugging Guide: IP Lookup, DNS & Speed Tests
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Understanding IP Addresses
Every device connected to the internet has an IP (Internet Protocol) address — a unique numerical identifier used to route data packets to the correct destination. There are two types of IP addresses you will encounter as a developer:
- Public IP address — The address your ISP assigns to your router. This is what websites see when you connect to them. Use our IP Lookup tool to find your public IP.
- Private IP address — The address assigned to your device within your local network (e.g., 192.168.1.100). Not visible from the internet.
Private IP ranges (RFC 1918): 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16. These are never routable on the public internet.
IP Geolocation: What It Can and Cannot Tell You
IP geolocation maps an IP address to a physical location using databases maintained by companies like MaxMind and IP2Location. It can typically identify:
- Country (95%+ accuracy)
- Region/State (80%+ accuracy)
- City (60-80% accuracy)
- ISP and organization name
- Timezone
- Whether the IP is a VPN, proxy, or Tor exit node
IP geolocation cannot determine exact street address, identify the specific person using the IP, or track mobile devices that change IPs frequently.
DNS Debugging Step by Step
When a website is not loading or email is not working, DNS is often the culprit. Here is a systematic debugging approach:
- Check if the domain resolves — Use our DNS Lookup tool to query A records. If no records return, the domain may not exist or DNS is misconfigured.
- Verify the IP is correct — Compare the returned IP with your server's IP. If they don't match, your DNS records are pointing to the wrong server.
- Check propagation — DNS changes take time to propagate. Query multiple DNS servers (8.8.8.8, 1.1.1.1, your ISP's resolver) to see if they return consistent results.
- Check TTL — If records are cached with a high TTL, old records may persist for hours. Check the TTL value in DNS records.
- Flush local cache — Clear your browser and OS DNS cache to force fresh lookups.
Understanding Internet Speed Tests
A speed test measures three key metrics of your internet connection:
Download Speed
How fast data travels from the internet to your device. Measured in Mbps (megabits per second). Affects streaming, browsing, and downloading files. Most home connections are asymmetric with faster download than upload.
Upload Speed
How fast data travels from your device to the internet. Affects video calls, file uploads, live streaming, and cloud backups. Typically 5-20% of download speed on cable/DSL connections.
Ping / Latency
The round-trip time for a data packet to travel to a server and back. Measured in milliseconds (ms). Critical for gaming, video calls, and real-time applications. Lower is better.
What is a Good Internet Speed?
| Use Case | Recommended Speed |
|---|---|
| Web browsing & email | 1-5 Mbps |
| HD video streaming (1080p) | 5-10 Mbps |
| 4K video streaming | 25+ Mbps |
| Video calls (HD) | 3-5 Mbps upload |
| Online gaming | 3-6 Mbps, <50ms ping |
| Remote work / VPN | 10-25 Mbps |
| Multiple users / devices | 100+ Mbps |
| Developer (large uploads) | 50+ Mbps upload |
Common Network Issues & Fixes
Slow speeds despite fast plan
Test with a wired connection. WiFi interference, distance from router, and network congestion can significantly reduce speeds. Also check if other devices on the network are consuming bandwidth.
High ping / latency
Close background applications, use a wired connection, connect to servers geographically closer to you, and check for network congestion during peak hours.
Intermittent connection drops
Check cable connections, restart your router and modem, check for ISP outages in your area, and test with a different DNS server (try 1.1.1.1 or 8.8.8.8).
VPN slowing connection
VPNs add overhead and route traffic through additional servers. Choose a VPN server geographically close to you and use a protocol like WireGuard for better performance.