Learning Objectives

This section doesn’t offer anything new but, by looking into how data flow across all the layers in the Internet stack, it will help your understanding of all the networking concepts and technologies you have learned so far. The journey starts with a Web page request, as we do almost every day.

Learning Tasks

Required

  1. Watch the slideshow for this section.
  2. Study Section 6.7, Retrospective: A Day in the Life of a Web Page Request, in the textbook.

Terms and Topics

Section 5 – Data Flow Across the Layers

DHCP
UDP
IP
Ethernet
DHCP request message
UDP segment
IP datagram
Ethernet frame
Multiplexing and demultiplexing
CIDR
DHCP ACK message
Self-learning switch
IP forwarding and IP forwarding table
TCP socket

HTTP request
DNS and DNS protocol
DNS query message
ARP protocol
ARP query and ARP reply
Intra-domain routing with RIP, OSPF, and IS-IS
Inter-domain routing with BGP
DNS resource record
Authoritative DNS server
DNS reply message
HTTP GET message
Three-way handshake
TCP SYN
HTTP response

Leading Questions

  1. When you request a Web page with a Web browser, what does the browser do to begin with?
  2. What networking protocols or services are triggered thereafter and in what order?
  3. What are DHCP request message, UDP segment, IP datagram, and Ethernet frame?
  4. What does demultiplexing do?
  5. What is CIDR?
  6. What type of information does a DHCP ACK message provide?
  7. We say some networking switches can be self-learning. What does that mean?
  8. What information does an IP forwarding table contain?
  9. What is a TCP socket?
  10. What format or formats does an HTTP request have?
  11. What does DNS protocol or a DNS server do?
  12. What information does a DNS query message provide?
  13. What does ARP protocol do?
  14. What information does an ARP query message provide?
  15. What information does an ARP reply message have?
  16. What are intra-domain routing protocols?
  17. How do RIP, OSPF, and IS-IS work?
  18. What are the Internet’s inter-domain routing protocols?
  19. What does the BGP protocol do?
  20. What are DNS resource records?
  21. What is an authoritative DNS server?
  22. What information does a DNS reply message contain?
  23. How does a Web browser interact with a Web server at the transport and application layer?
  24. What is an HTTP response?
  25. What may an HTTP response message contain?