IP, DNS and Subnet Tools
Network Tools answer the everyday questions of running anything on the internet: what is my public IP, who owns this address in my logs, what do resolvers return for this domain, how many hosts fit in this subnet, and which vendor made this network card. Developers, sysadmins, support engineers and students preparing for networking certifications use them.
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All Network Tools (8)
IP Address Info
Get detailed IP address informationIP Address Lookup
Get detailed information about IP addressesDNS Lookup
DNS record lookup and analysisSubnet Calculator
Calculate network subnets and CIDRPort Scanner
Simulated port scan results for learning how real scanners workMAC Address Lookup
Look up MAC address vendor informationIP Converter
Convert IPv4 addresses between dotted, integer, hex and binaryNetwork Tools
Your public IP, ISP and browser connection details
Which tool do I need?
Find my public IP before adding it to a firewall allow list
What Is My IP shows your IPv4 and IPv6 addresses. The Network Tools page adds browser details you can copy into a support ticket.
Identify who owns an IP address in my server logs
IP Address Lookup shows the organisation, autonomous system, reverse DNS hostname and approximate location from ipinfo.io.
Check the MX, SPF or CAA records for a domain
DNS Lookup returns ten record types at once with their TTLs. Query _dmarc.example.com separately for DMARC.
Plan address ranges for a VPC or an office network
The Subnet Calculator gives the network, broadcast, mask and usable host range for any prefix, and the IP Converter turns addresses into integers for range checks.
Identify the manufacturer of a device on my network
MAC Address Lookup normalises the address, extracts the OUI and reads the multicast and locally administered flag bits.
Learn what open, closed and filtered ports mean
The Port Scanner simulator produces a report in the shape of a real scan with service names, so you can learn the format before running nmap.
About Network Tools
Some of these tools have to call outside services, and each page says which. What Is My IP and the Network Tools browser info page ask api.ipify.org and ipapi.co for your public address and its location, IP Address Lookup sends the address you enter to ipinfo.io, and DNS Lookup queries Google Public DNS over HTTPS with Cloudflare and Quad9 as fallbacks. The Subnet Calculator, IP Converter and MAC Address Lookup do their arithmetic in the browser and send nothing. The Port Scanner is a simulator with random results, because a web page cannot open raw TCP sockets; use it to learn port numbers and the open, closed and filtered vocabulary, then run nmap or nc for real answers.
A few ideas tie the group together. The public IP websites see is usually your router's address after NAT, and geolocation describes the network, not where you sit. Authoritative servers show a changed record right away, but resolvers that cached the old answer keep returning it until its TTL runs out. Subnetting is prefix arithmetic on 32-bit integers, which is why the IP Converter's decimal form and the Subnet Calculator's masks are two views of the same number. Calculation here is IPv4 only; IPv6 addresses can be looked up but not subnetted. MAC vendor lookup uses a built-in table of 20 common prefixes, and a MAC address never crosses a router.
Guides
- How Subnetting Works: CIDR Prefixes, Masks and Host CountsWork out network, broadcast and host ranges for any IPv4 prefix, split a /24 cleanly, handle /31 and /32 correctly, and read addresses as 32-bit numbers.
- DNS Records Explained: A, AAAA, CNAME, MX, TXT, NS and CAAWhat each DNS record type does, how resolvers and TTLs decide what people see after a change, and how to check mail and certificate records properly.
- Public IP Addresses Explained: NAT, Geolocation and LookupsWhy every device in your house shares one IP, what CGNAT and IPv6 change, how accurate IP geolocation really is, and what IP lookup services can and cannot tell you.
- Port Scanning Explained: Open, Closed and Filtered PortsWhat a port scan actually sends, how to read open, closed and filtered results, why browsers cannot scan, and how to use nmap and nc responsibly.
Frequently asked questions
Which network tools send data to third-party services?
Four of them. What Is My IP and the Network Tools page contact api.ipify.org, api64.ipify.org and ipapi.co, IP Address Lookup sends the address you type to ipinfo.io, and DNS Lookup sends the domain to Google Public DNS and, as fallbacks, Cloudflare and Quad9. The Subnet Calculator, IP Converter, MAC Address Lookup and Port Scanner simulator send nothing.
Why do browser network tools use HTTPS checks instead of ping?
Web pages have no access to ICMP or raw sockets, so they cannot send a real ping or probe a port. Browser-based checks are built on HTTPS requests, which include TLS setup and server time, so their timings run higher than ping would show.
What is the difference between a public and a private IP address?
Private addresses come from the reserved ranges 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 and are routed only inside private networks and VPNs, never on the public internet. Your router translates them to its public address with NAT when traffic goes out, which is why websites see the router's address rather than your machine's.
How long does a DNS change take to show up everywhere?
Up to the TTL of the old record. Resolvers cache an answer for its TTL, so a record with a one-hour TTL can be served from cache for up to an hour after you change it. Lowering the TTL a day before a planned change makes the switch faster.
Do these network tools support IPv6?
Partly. What Is My IP shows your IPv6 address when you have one, IP Address Lookup accepts IPv6 addresses, and DNS Lookup returns AAAA records. The Subnet Calculator and IP Converter are IPv4 only, because IPv6 uses 128-bit arithmetic.