640 - 607
Leading the way in IT testing and certification tools, www.testking.com
- 11 -
Answer: C.
Explanation:
In general, IP addresses contain two fields: one for the network and another for host. Class A address have a
range of 1 to 126 and the network portion of the IP address is restricted to the first eight bits (octet). Class B
address have a range of 128 –191.255.0.0 and the network portion of the IP address is contain in the first 2
octets. Class C IP addresses has a range of 192.223.255.255.0 and the network portion of the IP addresses is the
first three octets of the IP address. Class D addresses include the range of 224.0.0.0 to 239.255.255.255 and are
used for multicast address. Class E addresses have a range of 224.0.0.0 to 247.255.255.255 and are reserved for
experimental purposes.
Incorrect Answers:
A is incorrect; although the subnet mask is used by network devices to determine what part of the IP address is
used for the network, the subnet and the host address but it is not part of the IP address hierarchy.
B is incorrect; the dots are used for making the IP address readable by humans, but have no determination of the
network number.
D is incorrect; DHCP (Dynamic Host Configuration Protocol) provides a mechanism for allocating IP addresses
dynamically so that addresses can be reused when hosts no longer need them.
E is incorrect; Address Resolution Protocol (ARP) determines the data link layer address of the destination
devices for known destination IP addresses network number.
Steve McQuerry. Interconnecting Cisco Network Devices. (Cisco Press: 2000) pages 215-227.
Q. 12
At which OSI layer does data translation and code formatting occur?
A. Physical
B. Data link
C. Network
D. Transport
E. Session
F. Presentation
Answer: F
Explanation:
The presentation layer provides a variety of coding and conversion functions that are applied to application
level data. These functions ensure that the data sent from the application layer of one system can be read the
application layer of another system.
Incorrect Answers:
A is incorrect; the physical layer is what puts the actual data onto the wire.
B is incorrect; the data link layer is involved in converting bits into bytes, converting bytes into frames and with
error detection.