# UGCNET-June2013-II: 18

5.7k views

In hierarchical routing with 4800 routers, what region and cluster sizes should be chosen to minimize the size of the routing table for the three-layer hierarchy?

1. 10 clusters, 24 regions and 20 routers
2. 12 clusters, 20 regions and 20 routers
3. 16 clusters, 12 regions and 25 routers
4. 15 clusters, 16 regions and 20 routers
in Others
1
I see the same question without options being asked. Is there a way to solve it directly , ans being 51. cube(17)=4913 but we have 4800 routers only. So how the ans is 51 , didn't understand that  part

$Clusters \times regions \times routers =4800 \text{ for all options}$

so we use following

$(clusters- 1) + (regions - 1) + routers$ , which option gives minimum is the ans...

Option 1 gives us 52.

Option 2 gives us 50

Option 3 gives us 51

Option 4 gives us 49

So the answer is D

edited
0
How the following formula came?

(clusters- 1) + (regions - 1) + routers , which option gives minimum is the ans...
2

that's how

(clusters- 1) + (regions - 1) + routers

0
Could you please explain further?

## Related questions

1 vote
1
848 views
Consider the following UNIX command: sort<in>temp; head-30<temp; nm temp Which of the following functions shall be performed by this command? Sort, taking the input from &ldquo;temp&rdquo;, prints 20 lines from temp and delete the file temp Sort eh file ... taking the input from &ldquo;temp&rdquo;, and then prints 30 lines from &ldquo;temp&rdquo; on terminal. Finally &ldquo;temp&rdquo; is removed.
A set of processors $P1, P2, \dots Pk$ can execute in parallel if Bernstein&rsquo;s conditions are satisfied on a pairwise basis; that is $P1 \parallel P2 \parallel P3 \parallel \dots \parallel Pk$ if and only if: $Pi \parallel Pj \text{ for all } i \neq j$ $Pi \parallel Pj \text{ for all } i =j+1$ $Pi \parallel Pj \text{ for all } i \leq j$ $Pi \parallel Pj \text{ for all } i \geq j$
A Boolean operator $\ominus$ is defined as follows: 1 $\ominus$ 1 =1, 1 $\ominus$ 0 = 0, 0 $\ominus$ 1 = 0 and 0 $\ominus$ 0 =1 What will be the truth value of the expression (x $\ominus$ y ) $\ominus$ z = x $\ominus$ (y $\ominus$ z)? Always true Always false Sometimes true True when x,y, z are all true