Download ReviewSheet Midterm1 Last modified January 7

COE 371
Student Name:
Midterm 1
Student ID:
Question 1 (27 points):
Circle the correct choice. No explanation needed.
1. Which station characteristic(s) can be used to group stations into a VLAN (Virtual LAN)?
(a) port numbers (b) MAC addresses (c) IP addresses (d) all of the above.
2. A bridge can _____. (a) filter a frame (b) forward a frame (c) extend a LAN (d) do all the
above.
3. A system with redundant bridges might have a problem with ___ in the system. (a) loops (b)
filters (c) spanning trees (d) all of the above.
4. A bridge never forwards frames out of the ___ port. (a) root (b) designated (c) forwarding (d)
blocking.
5. An ARP reply is ___ to __. (a) broadcast; all hosts (b) multicast; all hosts (c) unicast; all
hosts (d) unicast; one host.
6. An IPv4 address consists of ___ bits. (a) 4 (b) 8 (c) 32 (d) none of the above.
7. Class ___ has the greatest number of hosts per given network address. (a) A (b) B (c) C (d)
D (e) E.
8. On a network that uses NAT, the NAT router can use___ global address(es). (a) one (b) two
(c) a pool of (d) none of the above.
9. The default mask in a class C network is __. (a) 255.0.0.0 (b) 255.255.0.0 (c) 255.255.255.0
(d) 255.255.255.255
10. The IP protocol is ___. (a) connectionless (b) connection-oriented (c) obsolete now. (d) none
of the above.
11. A bridge changes __ of the frame it receives. (a) MAC address (b) IP address (c) neither
MAC nor IP address (d) both IP and MAC addresses
12. The following IP address cannot be assigned to a physical host in a system using classful
addressing with no subnetting. (a)192.13.14.15 (b) 192.12.14.255 (c) 192.12.14.0 (d) Both a
and b (e) Both b and c.
13. The DHCP server issues ____ address in response to a client’s request. (a) a MAC (b) an IP
(c) both MAC and IP (d) none of the above.
14. The network address corresponding to the IP address 128.6.7.9 is (a) 128.6.0.0 (b) 128.0.0.0
(c) 128.6.255.255
15. An IP datagram fragment has arrived with an M bit value of 1 and a fragmentation offset
value of 0. This is the ___ fragment of the IP datagram. (a) last (b) middle (c) first (d) none of
the above.
16. In a ___ service, the packets belong to a message are sent on the same path in sequential
order. (a) connection-oriented (b) connectionless (c) none of the above
17. Which field in an IP datagram controls the maximum number of hops visited by the
datagram? (a) HLEN (b) TTL (c) Protocol (d) Fragmentation Offset (d) none of the above.
18. In classless addressing, the number of addresses in an assigned block must be __. (a) 100 (b)
more than 2 (b) 2 (c) a power of 2 (d) a power of 16.
Question 2: [6 points]
What is the theoretical maximum number of subnets in class C using the following subnet masks?
(a) 255.255.255.128
(b) 255.255.255.0
(c) 2555.255.255.224
1
Question 3: [7 points]
Find the subnet mask that creates 25 subnets in class C.
Question 4: [10 points]
A company using classful addressing is given the network site address 136.0.0.0 . The company
needs 100 subnets. Find (a) the subnet mask to be used. (b) the number of hosts per subnet.
Question 5: [8 points]
An IP datagram with a data size of 5000 bytes is fragmented into three parts. The first fragment
carries bytes 0 to 1999, the second fragment carries bytes 2000 to 3999, while the third fragment
carries bytes 4000 to 4999. What will be values of fragmentation offset field for each of those
three fragments?
2
Question 6: [15 points]
Consider a system of 3 LANs and 4 bridges. The bridges (B1 to B4) connect the LANs as
follows:
B1 connects LAN 1 and LAN 2.
B2 connects LAN 2 and LAN 3.
B3 connects LAN 1 and LAN 2.
B4 connects LAN1 and LAN 3.
Choose B1 as the root bridge. Create a loopless topology, and show the forwarding and blocking
ports after applying the spanning tree procedure.
Question 7: [5 points]
Why do we need to fragment an IP datagram sometimes? Explain in at most four lines.
3
Question 8: [10 points]
In a class B subnet, the IP address of a host is 133.134.113.60 and the subnet mask used is
255.255.240.0.
(a) What is the subnetwork address of the subnet to which the host belongs?
(b) What will be the broadcast address within the subnet to which the host belongs?
Question 9: [12 points]
In classless addressing, a block of IPv4 addresses are assigned to a company. One of the assigned
address is 200.16.17.0 /26.
(a) What is the first address in the block?
(b) What is the last address in the block?
(c) What is the total number of addresses assigned to the company?
4