- But when actual message goes ,then there can be multiple paths?
YES, there can be multiple paths .
see here , Traceroute
can also report --> (A , R1 , R2 , R5 , B) (very less chances but still it can report like this )
can also report --> (A , R1 , R2 , R3 , B) --> in most of the cases you will get this
can also report --> (A , R1 , R4 , R5 , B) --> in most of the cases you will get this
Which path does traceroute report?
Ans : In most of the time Traceroute is going to give you correct route (path) but still there is chances that Traceroute will not report you the correct path. for better understanding You can see the result of Traceroute command by typing it many times most of the time you might get different route and some time same route . :)
for windows : tracert www.gateoverflow.in
for linux : traceroute www.gateoverflow.in
Explanation : Even though Traceroute is going to give Router at number of hops but when you put all them (router) together they need not form any path , But the chances are that we are going to send dummy packet immediately (within a fraction of second -> can see in my previous comment image ) therefore basic assumption is that routes will not change so dynamically (i.e. in 1 ms the route might not change ) the entire procedure might take 1 second , so most of the cases we get the perfect route AND Its is not always guaranteed which means you could also expect that there is something wrong is this . (like above image )
Traceroute is mainly used by Sender side to get to know the route .
FOR EXACT Route go for Record Route which is used by Network Admin & they can find the exact route . They will send only one packet and this one packet will go only through one route and they will find the exact route BUT in Traceroute we are sending many packets and they may take different route therefore every time we get a router which is at so and so hops and if you all them put together then they might not even form a path .
I hope NOW its clear to you . :)