Does anybody know how to make sure if your computer has a virus or not? but without the cost of money?

Consider a slotted aloha system, where the time slot equals the fixed duration of each packet. assume that there are 4 stations a,b,c,d sharing the medium. (a) stations a,b,c,d receive one packet each from higher layers at times 1.3, 1.5, 2.6,5.7 respectively. show which transmissions take place when, according to the slottedaloha protocol; describe all transmissions until all four packets have been successful.when needed, each station has access to the following sequence of random number, provided by a random number generator and drawn uniformly between 0 and 1: (1) station a draws numbers: 0.31, 0.27, 0.78, 0.9, 0.9, 0.11, 0. (2) station b draws numbers: 0.45, 0.28, 0.11, 0.83, 0.37, 0.22, 0. (3)station c draws numbers: 0.1, 0.2, 0.3, 0.4, 0. (4) station d draws numbers: 0.36, 0.77, 0.9, 0.1, 0.1, 0.1, 0.1, 0. (b) in slotted aloha, a station transmits in each time slot with a given probability. what probabilities would you assign to each of the four stations so as to: (i) maximize the efficiency of the protocol? (ii) maximize fairness among the four stations? (c) will the efficiency increase or decrease if we modify slotted aloha as follows: (i) get rid of slots and allow stations to transmit immediately? (ii) implement carrier sensing? (iii) implement collision detection? (iv) implement collision avoidance?

Match the feature to the network architecture. expensive to set up useful for a small organization easy to track files has a central server inexpensive to set up difficult to track files useful for a large organization does not have a central server client- server network peer-to-peer network

Assume you need to test a function named inorder. the function inorder receives three int arguments and returns true if and only if the arguments are in non-decreasing order: that is, the second argument is not < the first and the third is not < the second. write the definition of driver function testinorder whose job it is to determine whether inorder is correct. so testinorder returns true if inorder is correct and returns false otherwise. for the purposes of this exercise, assume inorder is an expensive function call, so call it as few times as possible!