Week 3 Summary Exercises

Which of the following are application-layer protocols? -Domain Name Service (DNS) -Post Office Protocol v3 (POP3) -File Transfer Protocol (FTP) -Internet Protocol (IP) -Telnet -Transmission Control Protocol (TCP) -User Datagram Protocol (UDP) -Secure Shell (SSH)

-Domain Name Service (DNS) -Post Office Protocol v3 (POP3) -File Transfer Protocol (FTP) -Telnet -Secure Shell (SSH)

For the following question, proper hexadecimal format is (0xYYYY) where Y will range in (0-9) or (A-F). Only proper formats will be accepted. Suppose that we send a DNS request with ID #4779. 1. What is the little-endian representation (hexadecimal)? 2. What is the big-endian representation (hexadecimal)? 3. Which representation is required for network communication? (Enter "1" or "2" without quotes)

1. 0xAB12 2. 0x12AB 3. 2

A client's browser sends an HTTP request to a website. The website responds with a handshake and sets up a TCP connection. The connection setup takes 2 sec, including the RTT. The browser then sends the request for the website's index file. The index file references 5 additional images, which are to be requested/downloaded by the client's browser. How many requests (including the initial request) must be sent by the browser? 1. With non-persistent HTTP? 2. With persistent HTTP?

1. 12 2. 7

The reserved port for FTP control is port _________.

21

The reserved port for SSH is port _____.

22

Convert the following units. Your answer should be a whole number with no text in the answer field: 32 MiB = ________ bits

32 x 8 x 2^20 = 268,435,456

A client in a network with a proxy server requests a 3 MiB file from an internet server, fakeservername.com. The average server has a 3.7 Mbps connection to fakeservename.com. The average response time between the network's proxy server and the internet origin server (including RTT) is 1.2 seconds for a small "header-only" HTTP request/response. The file requested by the client is currently in the proxy server cache, but the proxy server relays the client's request to the internet server with "if-modified-since". Assume that transmissions between the proxy and the origin servers are stream (not packets) at full bandwidth, with negligible propagation delay. How much time is saved is the file has not been modified? (Give answer in seconds, without units, rounded to two decimal places, so for an answer of 1.4233 seconds you would enter "1.42" without the quotes.)

6.8

A client's browser sends an HTTP request to a website. The website responds with a handshake and sets up a TCP connection. The connection setup takes 3.9 ms, including the RTT. The browser then sends the request for the website's index file. The index file references 21 additional images, which are to be requested/downloaded by the client's browser. Assuming all other conditions are equal, how much longer would non-persistent HTTP take than persistent HTTP? (Give answer in milliseconds, without units, rounded to one decimal place. For an answer of 0.01005 seconds, you would enter "10.1" without the quotes.)

81.9

Place the steps in the correct order for a complete e-mail communication: Alice's user agent sends message to her mail server; message placed in message queue. Bob uses his user agent to read the message. SMPT client sends Alice's message over the TCP connection. Client side of SMPT opens TCP connection with Bob's mail server. Bob's mail server places the message in Bob's mailbox. Alice uses her user agent to compose message and sent to Bob's email address.

Alice uses her user agent to compose message and sent to Bob's email address. Alice's user agent sends message to her mail server; message placed in message queue. Client side of SMPT opens TCP connection with Bob's mail server. SMPT client sends Alice's message over the TCP connection. Bob's mail server places the message in Bob's mailbox. Bob uses his user agent to read the message.

The following is a valid IP address: 130.154.465.201

False

The following is a valid IP address: 130.154.1.256

False

In the internet, an application-level protocol implementing email service would most likely utilize _______ as its transport-layer protocol.

TCP

The IMAP/POP3 application-layer protocols utilizes the _____ transport-layer protocol.

TCP

A client-side piece of data which is used to keep track of transactions between a client and server is called a cookie.

True

An FTP server maintains client states.

True

HTTP implements a conditional GET using if-modified-since.

True

HTTP implements caching by use of a conditional GET.

True

In a _____________________ architecture, one host is always on, and other hosts may connect and be continually serviced by this first host.

client-server

Protocol _______________ allows multiple protocols to work together.

interoperability

Consider the following: http://oregonstate.edu/img/audience/future-apply.jpg The Host Name is: __________________________ The Path Name is: __________________________ The URL is: ________________________ The TLD is: ________________________

oregonstate.edu /img/audience/future-apply.jpg http://oregonstate.edu/img/audience/future-apply.jpg EDU

The SMPT e-mail protocol is called a _________ protocol.

push

A paired IP address and port number is called a ____________.

socket

Consider the following: http://www.google.com/images/srpr/logo11w.png The Host Name is: ______________ The Path Name is: _______________ The URL is: __________________ The TLD is: __________________

www.google.com /images/srpr/logo11w.png http://www.google.com/images/srpr/logo11w.png COM

Consider the following: http://www.oregon.gov/SiteCollectionImages/branding/portal/bigfoot.png The Host Name is: _____________________ The Path Name is: ______________________ The URL is: ________________________ The TLD is: ________________________

www.oregon.gov /SiteCollectionImages/branding/portal/bigfoot.png http://www.oregon.gov/SiteCollectionImages/branding/portal/bigfoot.png GOV