Suppose computers A and B have IP addresses 10.105.1.113 and 10.105.1.91 respectively and they both use the same net mask N. Which of the values of N given below should not be used if A and B should belong to the same network?

Consider a network with 6 routers R1 to R6 connected with links having weights as shown in the following diagram

All the routers use the distance vector based routing algorithm to update their routing tables. Each router starts with its routing table initialized to contain an entry for each neighbour with the weight of the respective connecting link. After all the routing tables stabilize, how many links in the network will never be used for carrying any data?

Consider a network with 6 routers R1 to R6 connected with links having weights as shown in the following diagram

Suppose the weights of all unused links in the previous question are changed to 2 and the distance vector algorithm is used again until all routing tables stabilize. How many links will now remain unused?

A main memory unit with a capacity of $$4$$ megabytes is built using $$1M \times 1$$-bit $$DRAM$$ chips. Each $$DRAM$$ chip has $$1K$$ rows of cells with $$1K$$ cells in each row. The time taken for a single refresh operation is $$100$$ nanoseconds. The time required to perform one refresh operation on all the cells in the memory unit is