Instructor: Seung Bae Im
Closed Book, Closed Notes.
Note: Write your name on each page of answer sheet. Clearly label each answer. DO NOT WRITE ON THE BACK OF A PAGE!
Name:_______________________________
1. (40 Points) Mark your answers on this page.
(a) Given the following IP address in binary, what is its dotted decimal equivalent?
10000100 11110001 10011110 00100100 = ______ . ______ . ______ . ______
(b) For an ordinary subnetting, choose all the possible subnet masks.
____ 128
____ 192
____ 224
____ 240
____ 248
____ 250
____ 252
____ 254
(c) Identify the class of the following IP address: 179.1.2.3
____ Class A
____ Class B
____ Class C
____ Class D
____ Class E
(d) A device has two IP addresses. This device could be ___. Choose all that apply.
____ a Computer
____ a Bridge
____ a Router
____ a Gateway
____ a Repeater
(e) A host with IP address 132.241.158.36 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 132.241.158.36 with the subnet mask of 255.255.255.240 sends a message to a host with IP address 132.241.158.45. Does the message travel through any router?
____ Yes
____ No
(g) Which one should be the “supernet mask” to combine 8 class C address blocks?
____ 255.255.255.192
____ 255.255.255.224
____ 255.255.255.240
____ 255.255.255.255
____ None of the above
(h) A subnet mask of 255.255.240.0 allows how many hostids per subnet?
____ 28 – 2
____ 29 – 2
____ 210 – 2
____ 211 – 2
____ 212 – 2
____ None of the above
(i) Who is responsible for “reassembling” of “fragmented IP datagrams”?
____ Source host
____ A router at the destination network
____ A destination host
(j) Your company has a Class C address of 193.123.33.0. The network has four subnets; three more will be added later. Which subnet mask will give you the most host IDs per subnet?
____ 255.255.255.248
____ 255.255.255.240
____ 255.255.255.224
____ 255.255.255.192
2. (50 Points)
(a) State reason(s) why we need subnetting of a given(assigned) network address.
(b) Describe “Multiplexing/demultiplexing” of a protocol layer using TCP layer and IP layer interactions as an example.
(c) Describe TCP’s flow control mechanism including the term, “credt”.
(d) An IP module(on a host or a router) uses “MTU(Maximum Transfer Unit) table). Describe how the IP module uses this table.
(e) Describe fragmentation and reassembly process of IP datagrams including the term, “16-bit Identification” field and the “Fragment offset” field in an IP packet.
(f) Describe/contrast the “Well-known ports” and “Ephemeral ports”.
(g) Describe why all 1’s and all 0’s are not useable in either (sub)network address or host addresses.
(h) Internet address space(IPv4) is running out(not many addresses are left to be assigned).
What are the three solutions to the problem? Only list them.
(i) Describe how TCP adjusts its timeout duration dynamically.
(j) Explain how the ARP(Address Resolution Protocol) operates.
3. (10 Points) Point out the differences between RIP and OSPF.