HW3 - (1) DNS is a mapping between IP addresses and domain...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
(1) DNS is a mapping between IP addresses and domain names. Is this mapping one to one? (b) Is www.ust.hk an alias or a canonical name? (c) What command we can use to find the 13 root DNS servers’ ip addresses? (2) This question explores URL hashing for cooperative caching (see Section 2.9.1). Suppose an institution has three caches, referred to as cache-0, cache-1,and cache-2. Suppose that the URL hashing scheme operates as follows: (1) only the hostname 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 3 to get the hash position in the alphabet; (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 chache-2. For example, the URL http://aaa.bbb.com has the hash value 1+1+1+2+2+2+3+15+13(modulo 3)=1; a request for this URL is sent to cache-1. a. Determine to which caches requests for each of the following URLs will be directed:
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 2

HW3 - (1) DNS is a mapping between IP addresses and domain...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online