Priscilla’s Protocol Podcast (PPP)

IP Addressing

Wed, 23 Apr 2008 16:56:56 -0700

Each interface in an IP network has a 32-bit address. Because 32 is a large number, IP addresses are written in dotted-decimal notation. Each byte is converted to decimal and separated from the next byte by a dot, for example, 192.168.0.1. An IP address contains a network and host field. Each interface is configured with a network and host number, and an indication of the network field length. The length can be specified as a subnet mask (255.255.255.0) or in CIDR notation, such as /24.

Domain Name System

Wed, 19 Mar 2008 11:07:34 -0700

The Domain Name System (DNS) is an application-layer, client/server protocol that allows Internet users to reach servers by name, rather than by a numeric IP address. DNS is a protocol as well as a system of servers that provide naming. The servers implement a distributed, hierarchical database of Resource Records (RRs) that map names to addresses, addresses to names, and other information.

Tracing an Email

Tue, 26 Feb 2008 13:39:37 -0800

This is the 2nd podcast dealing with Internet email. In this podcast we introduce techniques for recognizing a phishing scam. Phishing is a popular Internet scam where the perpetrators send email falsely claiming to be a legitimate enterprise in an attempt to get the recipient to surrender private information such as a credit card number or bank account number. We also use this practical example to further our teaching of Internet protocols, and introduce IP addresses and DNS names.

Email Protocols

Thu, 21 Feb 2008 12:29:39 -0800

In this episode we discuss the protocols used for sending and retrieving email. This is the first of two episodes on email. The next episode will talk about phishing, a type of scam that uses email. In this episode we cover email protocols. Simple Mail Transfer Protocol (SMTP) is used for sending email and Post Office Protocol (POP) and Internet Message Access Protocol (IMAP) are used for downloading email.

Hyptertext Transfer Protocol

Sat, 16 Feb 2008 16:36:12 -0800

HTTP is the protocol that makes the World Wide Web (www) work. HTTP defines the messages that Web clients and servers exchange, and the actions that clients and servers should take in response to various commands and replies carried in the messages. When you enter a Uniform Resource Locator (URL) such as http://www.priscilla.com in your Web browser, the HTTP implementation on your machine sends a command to the Web server directing it to retrieve and transmit the requested Web page.