| No. | Time* | Source | Destination | Protocol | Message | Size* |
|---|---|---|---|---|---|---|
| 0.000s | 192.168.1.10 | 192.0.2.53 | DNS | 71 B | ||
| 0.016s | 192.0.2.53 | 192.168.1.10 | DNS | 87 B | ||
| 0.032s | 192.168.1.10 | 203.0.113.10 | TCP | 60 B | ||
| 0.048s | 203.0.113.10 | 192.168.1.10 | TCP | 60 B | ||
| 0.064s | 192.168.1.10 | 203.0.113.10 | TCP | 60 B | ||
| 0.080s | 192.168.1.10 | 203.0.113.10 | HTTP | 91 B | ||
| 0.096s | 203.0.113.10 | 192.168.1.10 | HTTP | 149 B |
The internet, made visible
Protocol Explorer is an interactive way to learn the conversations behind the internet. Instead of memorizing a list of acronyms, choose a protocol and watch messages move between a client, a server, and the services involved. The network diagram shows who is communicating; the packet flow shows what they exchange and in which order.
Start with a familiar task: opening a web page. A name may need resolving, a transport connection needs establishing, and an application sends its request. Separating those stages makes it easier to understand why DNS, TCP, HTTP, and TLS have different jobs even when they support the same browser action.
This free protocol explorer runs original teaching scenarios in your browser. It requires no sign-up or installation. The traces are illustrative: timestamps are synthetic, intermediate hops may be omitted, and some events group several messages. Use them to build understanding before reading specifications or analyzing real packet captures.
How it works
Search for a name such as DNS, TCP, or HTTPS, or browse the Core, Application, and Security categories. Selecting a scenario resets playback so you can start from its first event. The overview lists its purpose, typical ports, transport, and an approximate OSI layer.
Press Play to move through the scenario automatically, or use Step to advance one event at a time. Change the playback speed when you want a slower explanation. The highlighted path identifies the current sender and receiver, while the caption names the selected event.
Select an event number in the packet table to revisit that moment and read its explanation in Overview. Switch between Network and Sequence views to connect topology with message order. Reset to replay, then choose a related protocol and compare the steps.
Features
Explore web requests, addressing, routing, email, file sharing, wireless access, and secure tunnels. Each protocol has its own scenario and explanation. Category filters keep the library manageable, while search also matches descriptive text, so you can discover a protocol by the problem it solves.
The network view emphasizes the endpoints involved in each event. The sequence view places participants across the top and messages in order below them. Both follow the same selection, allowing you to change perspectives without losing your place in the conversation.
Pause, step forward, go back, or restart whenever a message deserves another look. The event explanation adds context beyond the short packet summary. On desktop, use keyboard shortcuts and full screen; on mobile, switch panels to keep the controls and diagrams readable.
Use cases
If networking is new to you, begin with DNS, TCP, and HTTP. Describe each message in your own words before advancing. The goal is to connect a protocol’s responsibility to an observable exchange, then recognize how several protocols cooperate to complete one task.
Practice explaining a three-way handshake, the difference between HTTP and HTTPS, or how a proxy changes the communication path. Sequence view gives you a structure for a spoken walkthrough. Follow the linked specification when you need details beyond the simplified scenario.
Developers and educators can use the diagrams to discuss clients, services, authentication boundaries, and tunnels. Compare a direct request with a reverse proxy or a VPN scenario. Treat the diagram as a teaching model, then document the additional components used by your own system.
Working with agents after learning the network basics? Our A2A documentation introduces agent communication, and the AP2 protocol guide explores agent payment authorization. These application-level topics build on the transport and security concepts shown here.
Examples
Select HTTP and follow the DNS query and answer, the TCP handshake, and the request for the home page. Notice that receiving an IP address is different from opening a connection. The final 200 OK belongs to the HTTP exchange; it is not a TCP acknowledgment. This example deliberately uses HTTP/1.1.
Switch to HTTPS and look for the TLS handshake between TCP setup and the protected request. The added exchange establishes encryption and server authentication. The HTTPS scenario shows TLS 1.3 over TCP; choose QUIC separately to see the different transport arrangement used by HTTP/3.
Select DNS and watch a resolver obtain an answer from an authoritative server. Follow the root and TLD referrals before the resolver reaches the authoritative server. Then compare DNS over HTTPS with DNSSEC: the former protects the resolver connection, while the latter authenticates DNS data. Encryption and authenticity solve different problems.
For the formal definitions behind these examples, read HTTP semantics (RFC 9110), TCP (RFC 9293), TLS 1.3 (RFC 8446), and DNS concepts (RFC 1034). Protocol Explorer summarizes selected exchanges rather than implementing every state described in those standards.
FAQ
Protocol Explorer is a free interactive learning tool for internet and network protocols. Select one of 33 scenarios, follow the network or sequence diagram, and inspect each event with a plain-language explanation. It is designed for understanding message exchanges rather than monitoring a live connection.
Search for TCP and select it from the protocol list. Use Step to follow SYN, SYN-ACK, and ACK, or press Play to advance automatically. The diagram highlights the sender and receiver, while the overview explains sequence numbers and acknowledgments. Switch to Sequence to compare the message order.
No. The explorer runs predefined teaching scenarios in your browser. It does not capture packets, inspect your network, or connect to the example endpoints. Times are synthetic, and an event can group multiple wire messages. Use a packet analyzer and authorized captures when you need evidence from a real system.
The library contains 33 scenarios across Core, Application, and Security categories. Examples include HTTP, HTTPS, DNS, TCP, UDP, IPv6, WebSocket, QUIC, TLS, SSH, DHCP, SMTP, IMAP, proxies, WireGuard, IPsec, and Modbus TCP. Each scenario includes its own message flow, protocol overview, and a specification link.
Yes. This explorer is free and requires no account, API key, or download. On mobile, switch between Protocols, the diagram, and Overview using the panel buttons. The packet table scrolls horizontally, and the workspace adapts to the browser window height. Playback and protocol selection work on both touchscreens and desktop browsers.
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