Take Home Exam Two – BD350
These questions are meant to be answered with either written paragraphs, mathematical solutions or diagrams, depending on what you think is appropriate. For questions in multiple parts, write the answer to each part in a separate line or paragraph.
1. 5
points - On a subnet of a class C that would be able to have up to 100 hosts on
it, create a subnet mask so as to most efficiently allocate IP numbers.
2. 5
points – How many hosts can be on the subnet with the mask represented by 11111111.11111111.11110000.00000000
and what class of address is it?
3. 10 points - Circuit and Packet Switching
a) Distinguish between circuit switching and packet switching.
b) At the router, describe the switching decision and information needed.
c) How might IP4/IP6 Quality of Service (QoS) apply to circuit and packet switching networks and the applications that use them?
4. 20 points –
a) What do the standards at TCIP/IP each layer specify? (Write a separate paragraph for each layer.)
b) What standard is likely to be used at each layer when you reach the Internet from home to connect with a web server?
c) What are messages called at the Internet layer?
d) What
are messages called at the Data Link Layer?
5. 30 points - Assume that we are using HTTP 1.1 and that HTTP connections have a communication process as in Figure 1 (below). Note that this diagram is only an example. For this problem, we are downloading an HTML web page containing textual data, three jpgs and an animated gif.
a) What class of client/server application might this be? Why?
b) How many TCP connections will be made? How many HTTP Request-Responses cycles will be generated?
c) For the entire web page, how many TCP-PDUs will be generated if the maximum TCP segment size is 1500 bytes, the webpage is 1,200 bytes in size, and each image is 22,000 bytes in size? Show your calculations.
d) Is this HTTP session connection oriented or connectionless? Why?
e) If we go on to browse multiple web pages at this web site, would you consider these HTTP sessions to be connection-oriented or connectionless? Why?
f)
Name some methods that are used to maintain “state”
information about an HTTP session on both the server and the client.
6. 30
points - Based on the following diagram and router tables, indicate the route
that packets with destination addresses (a) 230.14.95.100, (b) 245.100.18.50,
and (c) 100.175.203.14 will take if they are sent from “Host A”. Precisely indicate each route by naming, in
order (with associated IPs if applicable), the
routers, switches, hubs, and/or hosts that will see each packet as it heads to
its destination. Include the destination
in the answer list.
|
Router A |
||
|
Addr |
Mask |
Dest |
|
200.45.17.0 |
255.255.255.0 |
200.45.17.1
port, direct |
|
100.175.0.0 |
255.255.0.0 |
130.100.14.5 |
|
245.100.18.0 |
255.255.255.0 |
15.75.100.104 |
|
Default |
--------- |
15.75.100.104 |
|
Router Q |
||
|
Addr |
Mask |
Dest |
|
100.175.0.0 |
255.255.0.0 |
100.175.15.35 |
|
230.14.95.0 |
255.255.255.0 |
130.100.14.4
port, direct |
|
245.100.18.0 |
255.255.255.0 |
130.100.14.2
port, direct |
|
Default |
--------- |
15.75.100.102 |
|
Router Z |
||
|
Addr |
Mask |
Dest |
|
245.100.18.0 |
255.255.255.0 |
130.100.14.1 |
|
230.14.95.0 |
255.255.255.0 |
130.100.14.1 |
|
230.14.100.0 |
255.255.255.0 |
15.75.100.103
port, direct |
|
Default |
--------- |
5.1.1.1 |
Figure 1. HTTP Connection Diagram