Network tools
Subnets, DNS, IPs: the daily bread of network admins, done right.
NebulaTerm
A free, local SSH, serial and Telnet terminal for network engineers. Open source, no telemetry.
IPv4 Subnet Calculator
CIDR, masks, ranges and subnet splitting with a visual map of the address space.
Runs in your browser
DNS Lookup
Every record for a domain, plus a zone health read that flags missing MX, SPF, DMARC and CAA.
What Is My IP
Your public IP address, plus what your browser quietly reveals about you.
MAC Address Vendor Lookup
Find the manufacturer behind a MAC from its OUI, and flag randomized MACs.
Runs in your browser
Wildcard Mask Converter
Convert subnet mask, wildcard and CIDR three ways, with the Cisco ACL context.
Runs in your browser
WHOIS / RDAP Lookup
Owner, registrar, dates, nameservers and abuse contact for any domain or IP, via RDAP.
IP Geolocation Lookup
A verdict (hosting, VPN, mobile or residential) plus country, ASN, reverse DNS and a map, for any IP.
Reading in this category
NVIDIA Spectrum-6: what 102.4 Tb/s Ethernet changes
NVIDIA's Spectrum-6 is a 102.4 Tb/s per-chip Ethernet switch for the Vera Rubin platform, with co-packaged optics. What's real, what's marketing, and who it's for.
How to do a DNS lookup from the command line
DNS lookup from the command line: nslookup on any OS, dig on Linux and macOS, dig +short for just the answer, and @8.8.8.8 to query a specific resolver. The commands.
How to show your IP address from the command line
Show your IP from the command line: ipconfig on Windows, ip addr on Linux, ifconfig on macOS for the local address, and curl for the public one. The commands per OS.
How to change your DNS zone at OVH
Change your DNS zone at OVH in the DNS Zone tab: edit the A record to your server IP. The steps, the leftover-record trap, and how to check the change took.
How to flush the DNS cache on Linux
Flush the DNS cache on Linux the right way: resolvectl for systemd-resolved, plus nscd and dnsmasq. Find which resolver you run and confirm the cache cleared.
How to flush the DNS cache on Windows
Flush the Windows DNS cache in one command: ipconfig /flushdns. Why and when to do it, how to confirm the cache is empty, and what to try when it does not help.
How to see a saved WiFi password on Windows
Forgot a WiFi password your PC already knows? One netsh wlan command shows any saved WiFi password on Windows in clear text. Steps, a real example, and the gotchas.
What is DNS TTL? Cache, propagation and the values to use
TTL is the number of seconds resolvers may cache a DNS answer. How it really works, why propagation is mostly waiting, and the right TTL per situation.
What is a /24? CIDR notation and subnet masks, finally clear
A /24 is a block of 256 IPv4 addresses, 254 usable. What the slash number means, how masks work bit by bit, and how to size real networks.