Instructor: Seung Bae Im
Closed Book, Closed Notes. Do not write on the back of pages!!
Total
points are more than 100--Answer all questions!
Name:_______________________________
1. (40 Points) Mark your answers on this page.
(a) Given the following IP address in binary, what is its dotted decimal equivalent?
10100100 11110001 10011010 00101100 = ________ . ________ . ________ . ________
(b) For a subnetting scheme which does not allow all 0’s subnet and all 1’s subnet addresses, choose all the possible values for subnet masks.
____ 128
____ 192
____ 224
____ 240
____ 248
____ 250
____ 252
____ 254
(c) Identify the class of the following IP address: 224.1.2.3
____ Class A
____ Class B
____ Class C
____ Class D
____ Class E
(d) Point out the main difference between “Store-and-Forward switch” and “Cut-Through switch”.
(e) A host with IP address 132.241.158.67 with the subnet mask of 255.255.255.224 sends a message to a host with IP address 132.241.158.42. Does the message travel through any router?
____ Yes
____ No
(f) A host with IP address 132.241.158.34 with the subnet mask of 255.255.255.240 sends a message to a host with IP address 132.241.158.48. Does the message travel through any router?
____ Yes
____ No
(g) Which one should be the “supernet mask” to combine 16 class C address blocks?
____ 255.255.192.0
____ 255.255.224.0
____ 255.255.240.0
____ 255.255.255.0
____ 255.255.255.240
____ None of the above
(h) A subnet mask of 255.255.240.0 allows how many hostids per subnet?
____ 29 – 2
____ 210 – 2
____ 211 – 2
____ 212 – 2
____ 213 – 2
____ None of the above
(i) Who is responsible for “reassembling” of “fragmented IP datagrams”?
____ Source host
____ Destination host
____ A router at the destination network
____Any router which has a connection to a network with a larger MTU
(j) Your company has a Class C address of 193.123.38.0. You need to divide the given address space into different sizes using VLSM: two subnets with 62 hosts each and four subnets with 30 hosts each. What subnet masks(two masks needed) do you need to achieve it? Note: All 0’s and all 1’s subnet addresses are possible with VLSM.
____ 255.255.255.192
____ 255.255.255.224
____ 255.255.255.240
____ 255.255.255.248
____ 255.255.255.252
2. 4 point each unless otherwise noted.
(a) With a diagram compare the layers between OSI model and TCP/IP model. Clearly mark corresponding layers of each model. Also, on the TCP/IP model diagram, write the name of protocols on each layer.
(b) (6 points)Discuss why Internet society came up with CIDR(Classless Inter Domain Routing) and state the main idea behind CIDR.
(c) (6 points) What is the “Closed loop” problem for networks using bridges? What is the solution?
(d) Discuss why ARP is needed and describe how ARP works.
(e) Describe why TCP needs 3-way handshaking for connection establishment.
(f) Describe why all 1’s and all 0’s are not useable in hostid portion of IP address.
(g) (12 points) We say that “client-server computing” is achieved using TCP (or UDP) socket-to-socket communication. Describe “client-server computing” including the following terms: Concurrent server, well-known port number, server’s IP address, client, ephemeral port number, client IP address, child process.
(h) Draw the hierarchical diagram of DNS tree and name each level. Also, what is FQDN(Fully Qualified Domain Name)?
(i) What is the main function of ICMP protocol?
3. 5 points each
(a) What is “AS(Autonomous System)” in Internet routing?
(b) Point out the difference(s) between “IGP” and “EGP”. What are the most popular protocols in each category.
(c) (6 points) Point out the main differences between “Distance vector routing” and “Link state routing”.
(d) State why the IGP routing algorithms(i.e. Distance vector routing(RIP) and Link state routing(OSPF)) are not suitable for Internet backbone routing.