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INTERACTIVE LEARNING TOOL

Protocol Explorer

Explore internet protocols with animated messages, real arrival order and packet inspection.

Read the learning guides ↓
PROTOCOL EXPLORERLearn how the internet works
Now learningHTTP · Web communicationOverview · 5 steps
Learning progress0%
0 / 14 complete · 0 in progress
Client192.168.1.10Router192.168.1.1InternetDNS Resolver8.8.8.8Web Server203.0.113.10

Protocol overview

HTTP

Active

Hypertext Transfer Protocol

HTTP defines the messages exchanged by a browser and a web server. A client requests a resource, and the server returns a status, headers and often a body. In HTTP/1.1 the start line and headers are readable text; the body can carry HTML, images or other media.

Layer
Application (Layer 7)
Default port
80 (HTTPS: 443)
Transport
TCP
Data format
Text · headers + optional body
Common methods
GET, POST, PUT, DELETE, HEAD
Defined in
RFC 9110, RFC 9112
Read the complete guide ↗

Packet flow

DNSTCPRequestResponse
No.TimeSourceDestinationProtocolInfoSize
10.000s192.168.1.108.8.8.8DNSStandard query A www.example.com75 B
20.012s8.8.8.8192.168.1.10DNSStandard query response A 203.0.113.1091 B
30.024s192.168.1.10203.0.113.10TCP52344 → 80 [SYN] Seq=066 B
40.041s203.0.113.10192.168.1.10TCP80 → 52344 [SYN, ACK] Seq=0 Ack=166 B
50.058s192.168.1.10203.0.113.10TCP52344 → 80 [ACK] Seq=1 Ack=160 B
60.058s192.168.1.10203.0.113.10HTTPGET / HTTP/1.1114 B
70.076s203.0.113.10192.168.1.10HTTPHTTP/1.1 200 OK (text/html)132 B

NAVSPROUT · PROTOCOL FIELD GUIDES

See how the internet works.

Learn 14 internet protocols with interactive packet animations, sequence diagrams, byte decoding and self-paced lessons. Free, on NavSprout.

A PRACTICAL LEARNING PATH

From the first lookup to an encrypted page

Start with IP addressing, compare TCP and UDP, then follow DNS, HTTP and TLS. Continue with network configuration, diagnostics, email, file transfer and remote access. Every guide includes a step-by-step explanation, a common misconception and a local packet lab.

APPLICATION

HTTP

HTTP defines the messages exchanged by a browser and a web server. A client requests a resource, and the server returns a status, headers and often a body. In HTTP/1.1 the start line and headers are readable text; the body can carry HTML, images or other media.

5 lessons · open guide →SECURITY

HTTPS

See how a browser combines HTTP semantics with authenticated encryption. HTTPS protects the exchange between TLS endpoints, including paths, headers and bodies.

6 lessons · open guide →CORE

TCP

Build a reliable, ordered byte stream over an unreliable packet network. Observe connection setup, acknowledgement, retransmission and shutdown.

5 lessons · open guide →CORE

UDP

Send independent datagrams with an eight-byte transport header. UDP adds ports and a checksum but does not add delivery, ordering or retransmission.

5 lessons · open guide →CORE

IP

Follow an IPv4 packet through a router. IP supplies addressing and best-effort routing; transport protocols supply ports and additional delivery behavior.

4 lessons · open guide →APPLICATION

DNS

Resolve a domain through recursive and authoritative servers. Read query IDs, question names, record types, referrals and cache lifetimes.

5 lessons · open guide →APPLICATION

DHCP

Join an IPv4 network using Discover, Offer, Request and Acknowledge. A lease can include an address, subnet mask, router and DNS settings.

4 lessons · open guide →CORE

ICMP

Explore network diagnostics with echo requests, echo replies and time-exceeded errors. ICMP reports network conditions rather than carrying an application stream.

4 lessons · open guide →APPLICATION

SMTP

Submit a message using a mail envelope and a DATA body. Distinguish SMTP delivery from the POP3 or IMAP protocols used to access a mailbox.

5 lessons · open guide →APPLICATION

POP3

Retrieve messages from a mailbox through authorization, transaction and update states. POP3 has a simpler mailbox model than IMAP.

4 lessons · open guide →APPLICATION

IMAP

Work with server-side mailboxes, tagged commands, flags and selective fetches. IMAP supports a mailbox shared across several devices.

5 lessons · open guide →APPLICATION

FTP

Separate a persistent command connection from a data connection. Follow a passive-mode file download and interpret FTP reply classes.

5 lessons · open guide →SECURITY

SSH

Establish an authenticated encrypted channel for a remote shell. Separate server identity verification, user authentication and channel multiplexing.

5 lessons · open guide →SECURITY

TLS / SSL

Understand the TLS 1.3 handshake: key agreement, server authentication, transcript verification and encrypted records. SSL is a legacy name, not the protocol used in this lesson.

5 lessons · open guide →

Check your understanding

What does a 404 response mean?

Why it’s hereNAVSPROUT ORIGINAL

Reading definitions is easier when you can connect them to a packet. This first-party learning tool pairs static explanations with a visual lab, byte inspection and a short knowledge check. All course data and application resources ship with NavSprout.

  1. Choose DNS and follow the lookup from client to authoritative server.
  2. Switch to the sequence view, then inspect a packet and select a field to highlight its bytes.
  3. Compare TCP with UDP, answer the quiz and export your progress.

Frequently asked questions

What happens when I open a website?

A typical first HTTPS visit can involve DNS resolution, a transport connection, a TLS handshake and an HTTP exchange. Caches, connection reuse and HTTP/3 can change this sequence.

How are TCP and UDP different?

TCP presents a reliable ordered byte stream. UDP preserves individual datagram boundaries without built-in delivery guarantees. Applications choose the behavior they need.

Are these real captured packets?

No. Frames are generated locally for teaching. Header lengths and checksums are calculated, while TLS ciphertext and some negotiation payloads are illustrative. Downloaded PCAP files contain synthetic examples, not live traffic.

Can I learn without JavaScript or an account?

All 14 protocol guides and their lesson explanations are available as ordinary HTML without signing in. JavaScript powers animations, byte inspection, local progress and quizzes.

Where is my progress saved?

Only in this browser’s local storage. Export a progress JSON file to move it to another device. Clearing browser data can remove progress.

Standards and scope

Original NavSprout implementation, informed by IETF protocol standards. The lab focuses on IPv4, HTTP/1.1 and a conceptual TLS 1.3 flow. It is a teaching simulation, not a complete network stack.

TCP · RFC 9293 · HTTP · RFC 9110 · TLS · RFC 8446
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