Networking & Wireless forum

Question

RTT time for webpages (including DNS lookup)

I'm having trouble understanding this question. Can anyone help?......

Suppose within your Web browser you click on a link to obtain a Web page. The content of the web page is not cached in the local caching server, and the IP address for the associated URL is not cached in your local host either, so that a DNS look-up is necessary to obtain the IP address. Suppose that n DNS servers need to be visited before your host receives the IP address from DNS, and each of successive visits incur round trip delay of RTT1, RTT2 ... RTTn respectively. Further suppose that three images, sized 100KB, 120KB and 80KB respectively, are embedded in the Web page associated with the link, which are stored on the same web server as the web page itself, while the size of the Web page is 4KB. Let RTT0 denote the round trip delay between your computer and the server containing the web page, and let R denote the average end-to-end transmission rate between your computer and the Web server. How much time elapses from when you click on the link until you see the entire content of the web page associated with the link? Your calculation should include all the RTTs and transmission delays and show them in a properly simplified mathematical formula.

Would something like this make sense?

T = (2RTT0 / R) + (2RTT1 / R) + (2RTT2 / R) + (2RTT3 / R)

That's 2 RTT's for the webpage and 2 more for each of the 3 objects, each divided by the transmission rate?

Answer This Ask For Clarification
Discussion is locked
You are posting a reply to: RTT time for webpages (including DNS lookup)
The posting of advertisements, profanity, or personal attacks is prohibited. Please refer to our CNET Forums policies for details. All submitted content is subject to our Terms of Use.
Track this discussion and email me when there are updates

If you're asking for technical help, please be sure to include all your system info, including operating system, model number, and any other specifics related to the problem. Also please exercise your best judgment when posting in the forums--revealing personal information such as your e-mail address, telephone number, and address is not recommended.

You are reporting the following post: RTT time for webpages (including DNS lookup)
This post has been flagged and will be reviewed by our staff. Thank you for helping us maintain CNET's great community.
Sorry, there was a problem flagging this post. Please try again now or at a later time.
If you believe this post is offensive or violates the CNET Forums' Usage policies, you can report it below (this will not automatically remove the post). Once reported, our moderators will be notified and the post will be reviewed.

All Answers

Collapse -
Answer
Re: question

In reply to: RTT time for webpages (including DNS lookup)

That looks like homework for school. We don't help with that.

Moreover, it's an unanswerable question, because it doesn't include the processing time in the browser, the OS, antivirus and the videodriver and the fact that it makes a difference if the browser asks ask for the 3 pictures in parallel or not.

To see a real life example of processing in a browser visit any webpage after (in Firefox) pressing Tools>Webdeveloper>Network.

In your formula, I don't see the size of the webpage and the three images. So your answer certainly is wrong. Big pictures take more time than small pictures.

Collapse -
thanks

In reply to: Re: question

Thank you. I'll check out the Firefox tool.

Also, they're looking for a general formula, hence the actual transmission rate and time is excluded. I agree that it's worded rather strange though, which is why I'm having issues solving it.

Popular Forums

icon
Computer Newbies 10,686 discussions
icon
Computer Help 54,365 discussions
icon
Laptops 21,181 discussions
icon
Networking & Wireless 16,313 discussions
icon
Phones 17,137 discussions
icon
Security 31,287 discussions
icon
TVs & Home Theaters 22,101 discussions
icon
Windows 7 8,164 discussions
icon
Windows 10 2,657 discussions

DEALS, DEALS, DEALS!

Best Black Friday Deals

CNET editors are busy culling the list and highlighting what we think are the best deals out there this holiday season.