Networking · IPv4

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Subnet Calculator

See the bits. Learn the math. Type any IP and prefix length and watch the binary representation update live - network bits, host bits, broadcast address, usable range. Subnetting stops being magic the moment you see it as just bits.

IPv4 Subnetting Binary CIDR
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Networking · OSI Model

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Packet Journey

Follow a packet from your browser to a server and back. Watch every header get added and stripped. See NAT rewrite your IP. Watch MAC addresses change at every hop while IP stays the same. 18 steps. Every one of them real.

OSI Layers TCP/IP NAT Ethernet DNS ARP
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Networking · DNS

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DNS Resolver

Follow a DNS query from your browser all the way to the authoritative name server and back. Watch the recursive resolver walk the full hierarchy - root, TLD, auth - step by step. Includes live DNS lookups via Google's public resolver.

DNS Recursion TTL Caching Root NS
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Networking · TCP

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TCP Handshake

Watch the 3-way handshake form and tear down. Real sequence numbers. Every state transition. Then flip to chaos mode - drop a SYN and watch exponential backoff, trigger a server RST, or kill a live connection mid-flight.

TCP Handshake State Machine RST Retransmit
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Networking · NAT

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NAT Visualizer

Watch how your router rewrites packets so many devices share one public IP. See the NAT table fill in live. Understand why inbound traffic gets blocked by default โ€” and how port forwarding punches through. Four scenarios, step by step.

NAT PAT Port Forwarding Private IP
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