HW2Solutions

HW2Solutions - IT 420 Spring 2011 Homework 2 Solutions 1....

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IT 420 Spring 2011 Homework 2 Solutions 1. Answer questions 4.10, 4.12 and 4.27 on page 80 of the textbook. For this homework only, I will provide the questions because some students may still not have the textbook. 4.10 Describe the steps a browser takes to determine whether to use an item from its cache. A browser saves the Last-Modified date information along with the cached copy. Before it uses a document from the local cache, a browser either makes a HEAD request to the server and compares the Last-Modified date of the server’s copy to the Last-Modified date on the cached copy or uses if-modified-since in the request. If the cached version is stale, the browser downloads the new version. 4.12 When a user requests an FTP directory listing, how many TCP connections are formed? Explain. FTP uses two types of connections to perform its functionality, namely A control connection is reserved for commands. Each time the server needs to download or upload a file, the server opens a new connection. A data connection is used to transfer files. 4.27 True or false: A DNS server can return a different IP address for a given name, depending on whether the lookup specifies email or web service. Explain. Yes, a corporation may decide to use the name corporation.com for both web and email services. With the DNS, it is possible for the corporation to divide the workload between separate computers by mapping type A lookups to one computer and type MX lookups to
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HW2Solutions - IT 420 Spring 2011 Homework 2 Solutions 1....

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