1. A user message is split into 15 frames, each of which has an 80% chance of arriving error-free. If no error control is used by the data link layer, how many times must the message be sent on the average to get the entire message through?
2. A communication channel has a bit rate of 14 kbps and an one-way propagation delay of 10 msec. If the sender sends one frame and waits for an acknowledgment before proceeding, what range of frame sizes gives an efficiency of at least 50%?
3. A 200 km long cable operates at T1 rate. The propagation speed in the cable is 2/3 of speed of light (200,000 km/sec). How many bits can fit in the cable?
4. A group of N stations share a 64 kbps pure ALOHA channel. Each station generates a 1000-bit frame on an average of once every 100 second, even if the previous frame has not yet been sent (i.e. frame is buffered). What is the maximum value of N?
5. 10,000 travel agents are competing for the use of a single slotted ALOHA channel. The average agent sends 36 requests / hour. A slot time is 125 usec. What is the appropriate total channel load?
6. Consider building a 10Gigabit Ethernet running over a 1-km optical cable with no repeaters. The signal speed in the cable is 200,000 km/sec. What is the minimum frame size?© BrainMass Inc. brainmass.com October 24, 2018, 5:47 pm ad1c9bdddf
General E-commerce questions
What is a benefit of e-auctions to sellers?
-Convenience since the bidding can occur anywhere and anytime
-High stickiness to the web site
-The optimal price is determined by the market
Because online buyer's decisions depend on numerous independant and intervening variables, decsions made by customers are classified as?
All of the following are types of communication and collaboration done in real time EXCEPT?
Most universities use e-learning?
-exclusively in reaching students who couldn't otherwise attend classes
-only when forced by administrators to use it as a way to recruit distant students or reduce cost
-as a total replacement for traditional classrooms
-as a supplementary channel to traditional classrooms
A_______is suitable for mobile users who need to make very short-range device to device wireless connections within a small space, such as a single room, and most commonly with Bluetooth?
-wireless area network
-local area network
-personal area network
-Wi-Fi area network
_______work best with may buyers and sellers?
A card that draws the payment directly from the users checking account is called a (an)?
The _____pricing strategy means adding up all the costs involved, such as material, labor, rent, overhead and so forth and adding a percentage mark-up as profit.
All of the following are ways to use the internet to find information about an individual EXCEPT?
-stealing an individuals computer
-using cookies, spyware, or keystroke loggers
-wiretapping communications lines
-reading an individuals email, IM blogs or text messages
Key strategies for successful online community include all of the following EXCEPT?
-increasing traffic and participation in the community
-controlling the sharing of information or sensitive opinions
-focusing on the needs of the members, use facilitators and coordinators
-obtaining financial sponsorship