329E
Homework CS 1
1) Explain the terms circuit switching and packet switching. Discuss the advantages and
disadvantages of both.
a. Circuit switching: there is a dedicated circuit for each communication. Its
guaranteed performance but if the link is broken information cannot be shared
between two nodes also the link is idle if not being used.
b. Packet switching: data is sent over the network in small chunks that are sent to
routers and sent to other routers until they reach the destination. Different users
share the same network resources, if there are many packets in the network this
causes congestion and packets get dropped causing information loss.
2) How is an Ethernet network different from a token ring network? What is the role of a
repeater, bridge, and switch in an Ethernet network?
a. A token ring uses a token in order to grant access to stations who need to send
data while Ethernet has no such token so multiple stations can send data
simultaneously.
b. Ethernet repeaters and switch are used to build larger Ethernet networks and also
keeps an eye out for collisions. Ethernet bridge is used to communicate to the data
link layer so only complete packets are forwarded (from the repeaters)
3) How is the Simple Mail Transfer Protocol (SMTP) different from either IMAP or POP
mail client access protocols.
a. SMTP transports e-mail among mail servers while POP only copies messages
from server to client and IMAP only copies message headers and transfers the
body.
4) There is the traditional seven-layer OSI networking model. What are the parallels and
contrasts that you see with the five-layer Internet model that we discussed in class?
a. The seven-layer OSI model has a few of the same layers that are in the five-layer
model (Physical, Network, Transport, Application) It also has Data Link, Session
and Presentation
b. The Internetwork and Network interface layer seems to be broken up and merged
into Network and Data Link layers
c. The Application layer seems to be broken up into session, presentation and
application layers.
5) What is a Datagram? Is there an advantage of using UDP over TCP?
a. A datagram is the transfer unit in packet switching networks
b. UDP is more advantageous when the speed of delivery is more important than the
accuracy of data (such as online gaming)
6) What are the functionalities (services provided) of the Apache Web Server? How does
that with contrast those of the IIS Web Server?
a. Apache web server has many compiled modules and supports various common
languages (Perl, Python, Tcl, PHP). It also allows virtual hosting and configurable
error messages.
b. IIS also features all the languages as Apachi and in adition has .NET integrated.
Also, IIS on the other hand focuses more on security and authentication
mechanisms therefore it is used more often in corporate environments.
7) What are typical values for phone modem speeds? How do those compare with DSL
modems, cable modems, ISDN, T1, T2, and T3. What are T2 and T3 lines? What are
typical speeds for optic cables? How fast are bit rates for wireless LAN networks and
satellite transmissions?
a. Phone modems are typically 56 kbps, DSL modems are faster ranging from 100s
of kbps to a 1-2 mbps, Cable ranges from 100s of kbps to 10s of mbps. T1is at
1.5mbps, T2 is at 6mbps and T3 can go up to 50 mbps. Typical ISDN speeds are
about 100kbps. Wireless LAN bit rates can range from 1-100 mbps. Fiber optic
cables can have speeds of 111gbps or more. Satellite transmissions are slower
than all others and bit rates can range from 1mbps.
8) What is the purpose of a MIME type specification in a request / response transaction
between a browser and a server?
a. MIME is an internet standard that supports emails with various texts, attachments,
multiple parts, header and other information. It has also grown from his purpose
into describing internet content in general.
9) Discuss the steps in a HTTP transaction. How are the headers in GET and POST
transactions different?
a. An HTTP client opens a socket and sends a request to the HTTP server; the server
sends the message and closes connection. The request has three parts: method
name, path to resource and version of HTTP.
b. The response also has three parts: HTTP version status code and description of
code
c. A complete response has the requested data (webpage) which is displayed by the
browser.
d. GET and POST headers are different because GET is asking to retrieve
documents while POST sends data to server which is used in CGI.
10) What is the purpose of the Common Gateway Interface?
a. CGIs purpose is to create an interface between the browser and the server which
can run a program on the web page. These programs are written in many different
languages but use a CGI script in order to run them on the web page.