How a Web Page Reaches Your Screen · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

From web address to page

Computing · Computer Systems · ages 15-16
Name ______________________   Date ____________

  1. A DNS lookup for wikipedia.org succeeds. What information does it supply for contacting the site?

    • An IP address for the hostname
    • The HTML resource selected by the page's path
    • The order in which the browser must lay out the page

  2. A browser has read a web address but has no saved IP address for its hostname. What must it do before contacting that server?

    • Ask DNS to return the HTML resource named by the path
    • Find an IP address for the hostname
    • Send the path as an IP destination without resolving the hostname

  3. A browser has no cached page or saved IP address for a site. Hostname lookup fails, although the server works. What follows?

    • The server sends the page through DNS instead of HTTP
    • The browser contacts the server using the path as its IP address
    • The browser cannot obtain the page by that hostname

  4. Which component answers a web request by returning stored files or generating response content?

    • The browser
    • The server
    • The DNS resolver

  5. Which web technology controls presentation such as colours and layout?

    • CSS
    • HTML
    • DNS

  6. What does HTTP 504 Gateway Timeout report?

    • The browser created an HTTP status because its own local waiting timer expired
    • DNS could not resolve the hostname, so no server supplied an HTTP response
    • A gateway did not receive a timely response from a needed upstream server

  7. A browser's cache permanently stores every website, so web servers are no longer needed.

    Circle one:   True   False

  8. A ping test reports Destination Host Unreachable. Which conclusion is supported?

    • A website gateway returned an HTTP 504 response
    • The computer or a router reports a delivery problem
    • The destination is definitely off and the test packet definitely left the computer
LightMySky · lightmysky.comW1-mt_8JveAW2Mg7-s1

Answer key

For grown-ups. Fold this page away before handing over the rest.

From web address to page W1-mt_8JveAW2Mg7-s1

  1. An IP address for the hostname · DNS supplies address information. It does not return the requested HTML or determine page layout.
  2. Find an IP address for the hostname · The browser needs a destination IP address to contact the server. DNS can look up addresses for the hostname.
  3. The browser cannot obtain the page by that hostname · The browser lacks both a usable address and a cached page. A working server does not fix failed hostname lookup.
  4. The server · The server supplies the response. The browser processes it; DNS lookup supplies address information.
  5. CSS · CSS controls presentation. HTML describes content and structure; DNS looks up addresses.
  6. A gateway did not receive a timely response from a needed upstream server · The gateway sends 504 after an upstream timeout. A browser's own timeout and failed DNS lookup are different events.
  7. False · A browser can cache some resources for reuse. That is not a permanent copy of every website.
  8. The computer or a router reports a delivery problem · This reports a network delivery problem. It does not establish one certain cause or prove the packet left the computer.
Worksheet · LightMySky