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📝 Sequence Builder

Network Processes

DNS Lookup
Packet Switching
Sending Email

🔍 How DNS Lookup Works

DNS (Domain Name System) translates human-readable domain names (like google.com) into IP addresses (like 142.250.180.14) that computers use.

The Process

  1. User types URL (e.g., www.example.com) in browser
  2. Browser checks local cache for IP address
  3. If not cached, request sent to DNS resolver (usually ISP)
  4. DNS resolver checks its cache
  5. If not found, resolver queries root DNS servers
  6. Root server directs to TLD server (.com, .org, etc.)
  7. TLD server directs to authoritative DNS server
  8. Authoritative server returns the IP address
  9. IP address cached and returned to browser

🎯 Correct Order

📦 Steps

📦 How Packet Switching Works

Packet Switching is how data travels across the internet. Large messages are broken into small packets that travel independently and reassemble at the destination.

The Process

  1. Data is split into small packets
  2. Each packet gets a header with source, destination, and sequence number
  3. Packets are sent independently across the network
  4. Routers read destination address and forward packets
  5. Different packets may take different routes
  6. Packets arrive at destination (possibly out of order)
  7. Destination uses sequence numbers to reassemble
  8. Missing packets are re-requested

Advantages

  • Efficient use of network capacity
  • Fault tolerant - if one route fails, packets find another
  • Multiple communications share same lines

🎯 Correct Order

📦 Steps

📧 How Email Sending Works

Email uses several protocols: SMTP (sending), POP3/IMAP (receiving). Here's how an email travels from sender to recipient.

The Process

  1. User composes email in email client (e.g., Outlook, Gmail)
  2. Email client connects to sender's mail server via SMTP
  3. Sender's server uses DNS to find recipient's mail server
  4. Email transferred to recipient's mail server via SMTP
  5. Email stored in recipient's mailbox on server
  6. Recipient's email client connects to their server
  7. Email downloaded via POP3 (download & delete) or IMAP (sync)

Key Protocols

  • SMTP - Simple Mail Transfer Protocol (sending)
  • POP3 - Downloads emails, removes from server
  • IMAP - Syncs emails, keeps on server

🎯 Correct Order

📦 Steps