Suppose an institution has four caches, referred to as cache-0, cache-1, cache-2 and cache-3. Suppose that the URL hashing scheme operates as follows:

(1) only the host name of the URL is used.

(2) all non-alphabetic characters are ignored.

(3) each alphabetic character is assigned a number corresponding to its position in the alphabet.

(4) these numbers are added modulo 4 to get the hash value of the URL.

(5) if the hash value is 0, the request is directed to cache-0; if 1, the request is directed to cache-1; if 2, the request is directed to cache-2; if 3, the request is directed to cache-3.

For example, the URL http://aaa.bbb.com has hash value 1 + 1 + 1 + 2 + 2 + 2 + 3 +15 + 13(modulo 4) = 0; a request for this URL is sent to cache-0.

[a] Determine to which caches requests for each of the following URLs will be directed:
www.ohecampus.com; www.liv.ac.uk; www.eurecom.uk; www.tiet.ac.in; www.w3c.net; www.embanet.com

[b] Suppose the institutional caches are initially empty. During the first morning of operation, the requests from users at the institution include http://www.ohecampus.com/admissions/index.phtml, http://www.ohecampus.com/programmes/msc.phtml, http://www.ohecampus.com/finance/loanscholarship.phtml, http://www.ohecampus.com/about/brochure.phtml. During the afternoon of the same day, there are seven requests to each of these URLs. Which servers (origin and cache servers) will satisfy these 32 requests?

[c] Suppose now on the second day of operation a fifth cache is added, cache-4 and the algorithm in the browsers is changed to calculate the hash value using modulo 5 rather than modulo 4. Suppose now requests are made for the same six URLs listed in Part a of this problem. What will happen?