Q$5$a$.[$Points $5]$ A process P$1$ at site A sends a request message to process P$2$ on site B$.$ Sites A and B are connected via internet. Typically, P$2\text{'}$s reply comes within $1$ minute. In this case, however, it has not received a reply even after $5$ minutes. What can be concluded from here? List all possible causes for this phenomenon $($there are several$).$

Q$5$b$.[$Points $5]$ Why is it easier to achieve scalability in a distributed system as compared to a centralized system? Illustrate using an example.

Q$5$c$.[$Points $5]$ State three important features for each of $($i$)$ Type $1$ Hypervisor and $($ii$)$ Type $2$ Hypervisors.

Q$5$d$.[$Points $5]$ In distributed file systems, in the context of cache update policy, two policies are popular: $($i$)$ write$-$through policy $($ii$)$ delayed$-$write policy. Briefly discuss the advantages and disadvantages of each of these policies.