Articles & Guides
Useful resources for web developers and system administrators
Found 39 · Networking · Reset
Networking
DNS, CDN, TLS or Origin: How to Isolate a Web Outage
A web request crosses five layers and each fails identically in a browser. Test them in order, one command per layer, and find the real cause in minutes.
Networking
How to Find a Server Port: Your Own, Remote and Proxy
How to find a server port: which port your service listens on in Linux, Windows and macOS, which port a host answers on, and where the proxy port lives. Real commands.
Networking
How to Find an IP Address: Your PC, Router and Server
How to find an IP address: public vs local, your computer on Windows, macOS and Linux, the router gateway and any server. Real ipconfig, ip a, dig and nslookup commands.
Networking
Static vs Dynamic IP Address: Differences, Examples, How to Check
Static vs dynamic IP explained: how DHCP leases work, whether 192.168 is static, how to check your IP type on any OS, and when a static IP is worth paying for.
Networking
Subnet Mask Cheat Sheet: /8–/32 Table and How to Calculate It
Subnet mask table from /8 to /32 with hosts per prefix, why 255.255.255.0 equals /24, how to find your mask on Windows, macOS and Linux, and wildcard masks.
Networking
How to Check Ping: Internet, Server, and Website
How to check ping to a server, website, or your internet connection: the ping command on Windows, macOS, and Linux, online ping from another network location, a table of normal ping values, and a diagnostics checklist for high or unstable ping.
Networking
Cloudflare Blocked in Russia? Why Sites Fail and How to Fix It
Cloudflare blocked in Russia: why sites stall at 16 KB or fail on ECH, how to test from a Russian vantage point, and the DNS and CDN fixes that restore access.
Networking
Fix ERR_ADDRESS_UNREACHABLE: Causes and Solutions
ERR_ADDRESS_UNREACHABLE means the IP resolved but there is no route to it. Learn the causes — router, VPN, IPv6, private IPs — plus diagnostics and fixes.
Networking
How to Check Open Ports: Online, Windows, Linux
How to check open ports: netstat and Get-NetTCPConnection on Windows, ss and lsof on Linux, nc and telnet from outside, plus a free online port scanner.
Networking
SMTP Errors 550 and 554: Causes and Fixes
SMTP errors 550 and 554 explained: what the codes mean, enhanced 5.x.x status codes, rejection causes (SPF, DKIM, DMARC, blacklist) and how to fix them fast.