 Welcome to week 2 of this course on demystifying networks. Last week, we saw how a network is made up of different layers and how protocols define rules between these layers to communicate and what role do addresses play in this communication. And we also wanted to understand what roles do the routers play. So, what we did was we saw an analogy of Dabawala's. So, the Dabawala's are known for routing difference in the entire city of Mumbai. And by this analogy, we try to understand how routing works. To summarize the Dabawala analogy, we saw that there are three types of Dabawala's. One at the source who brings Dabawas from homes to the train station. The second type of Dabawala's are present in the trains who sort these Dabawas. And the third type of Dabawala's get those Dabawas at the destination station and deliver it to their respective destinations. So, now you have a summary of what the roles of Dabawala's are. It's a good time to take a question. So, we have a reflection spot question for you. So, you may pause the video for a while and make a note of your answer and then you may continue watching. Based on the Dabawala's delivery process, find the correct combination of Dabawala roles and the piece of address relevant to that role. A, Dabawala's at source. The piece of information is source street and destination station. B, Dabawala's in train, source station and destination station. C, Dabawala's at destination, destination station, destination building and destination flow. And D, Dabawala's in train, destination station and Dabawala number. Some of you might have picked the option A. But here, the Dabawalas need to know the source station along with the source code but not the destination station. So, this is an incorrect option. And for those who have picked option number B, the Dabawalas in the train need to know the Dabawala number of the destination station to arrange the Dabbas in that category. In case of option C, the destination Dabawala can identify his Dabba only if his code is present on the Dabba but not in other cases. So, option C is also incorrect. And finally, option D. The Dabawalas in the train require just two pieces of information which is the destination train station and the destination Dabawala number who will collect the Dabba. So, option D is the correct option. Now, we have another reflection question. You can read the question, pause the video, pick your option and then continue watching the video. Imagine you are at Tiffin box, classify the Dabawalas into the below mentioned roles based on the definitions that will help you reach the destination. A router is one who knows the entire city and tells the paths to be taken on crossroads. A switch is one who knows the locality well and tells which lanes to traverse to reach a crossroad or destination. The options are A, all Dabawalas are switches, option B, all Dabawalas are routers, option C, source and destination Dabawalas are routers and train Dabawalas are switches, option D, source and destination Dabawalas are switches and train Dabawalas are routers. So, some of you might have selected the option A. So, as we heard from the definition, the switching Dabawalas know their localities very well. So, if we look at the two roles of the Dabawalas, the source and the destination Dabawalas are required to know their locality well because they pick the difference and drop the difference. Hence, all of them cannot be the switching Dabawalas. Some of you might have picked option B, that is all Dabawalas are routers. However, a router will know only when a crossroad comes and it knows the city very well but not the locality. So, all Dabawalas cannot be routers but there needs to be some switches too. And now you might have guessed the right answer. Yes, the right answer is D. So, based on the previous two explanations we see that the Dabawalas in the train are the ones who are routing the Dabawas from one place to the other whereas the Dabawalas the source and destination are switching the Dabawas which is they know the locality very well unlike the Dabawas in train who know the entire city very well. Hence, the option D is the correct option.