|
|
|
|
|
|
|
| 640 - 607 |
128 | 64 | 32 | 16 | 8 | 4 | 2 | 1 |
|
x | x | x | x | x |
|
|
| 5 bits of subnetting for network |
|
|
|
|
| x | x | x | 3 bits of subnetting for host |
So, the value is 128+64+32+16+8 = 248
Incorrect Answers:
A and C are incorrect; it is not even a valid subnet mask, a valid subnet mask is a continuous string of one bits, then followed by a continuous string of zero bits. Answer A and C both break this rule.
B is incorrect; this is a full Class C subnet mask, and only provides for ONE network, and we need 28. E is incorrect; this gives us 6 bits of network, and the problem calls for 5.
Steve McQuerry. Interconnecting Cisco Network Devices. (Cisco Press: 2000) pages
Q. 220
What was the key reason the International Organization for Standardization released the OSI model?
A.Users could access network server faster.
B.Different vendors networks could work with each other.
C.The industry could create a standard for how computers work.
D.The network administrator could increase the overall speed of their network.
Answer: B.
Explanation:
The ISO model separated the various functions so that a vendor did not have to write an entire stack. One vendor could write device drivers for their device, and not worry about higher layers, and the work can be contained and modularized. This also speeds up the process of bringing a product to market, as it minimizes code that a vendor needs to write.
Incorrect Answers:
A is incorrect; the ISO model does not make things faster, overall they might slow things down a bit because of the overhead of passing data through the layers.
C is incorret; this ISO model is for networking, not computer functions. D is incorrect; the ISO model does not provide any speed boost.
Steve McQuerry. Interconnecting Cisco Network Devices. (Cisco Press: 2000) pages
Q. 221
Each department has its own file server and the company has an enterprise server that is shared by all departments. What does a network administrator use to provide a secure separation between the management and sales department?
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