NAME:- MOHD. SHAHNAWAZ ALAMROLL NO:-COURSE:-B.SC (IT)SEMESTER: - THIRDBOOK NO:- BT0078(WEBSITE DESIGN)SESSION:- SPRING 20121. What are the requirements for an internet connection?you have to have a modem, a phone line / LAN cable wire/ and a wireless router (if you plan touse wireless connection). Make sure you have an ISP (internet service provider) If you wouldlike to get access to the internet at home, youll need an Internet Service Provider (ISP) and amodem to connect to the ISP. ISPs often provide a device called a router to let you share aninternet connection over a local area network, which means more than one computer in yourhouse can use the broadband connection at the same time. The devices are connected withcables and a hub or switch.A good place to start looking for an ISP is the Internet Service Provider Association (ISPA).Although this is a voluntary body its recognised by government for its knowledge andexpertise. All ISPs listed on the ISPA site have agreed to certain rules and standards set by theISPA. This means you can be confident an ISP listed by ISPA has good business practice.Similarly, you might find it helpful to get recommendations from friends who have an ISP asthere is no better substitute for getting a recommendation from someone you trust. If you aregoing to look for the ISP on your own try to get as much information as you can about whatthey offer.2. Briefly explain the transparent graphics.Transparency is possible in a number of graphics file formats. The term transparency is used invarious ways by different people, but at its simplest there is "full transparency" i.e. somethingthat is completely invisible. Of course, only part of a graphic should be fully transparent, or therewould be nothing to see. More complex is "partial transparency" or "translucency" where theeffect is achieved that a graphic is partially transparent in the same way as colored glass. Sinceultimately a printed page or computer or television screen can only be one color at a point, partialtransparency is always simulated at some level by mixing colors. There are many different ways
to mix colors, so in some cases transparency is ambiguous.In addition, transparency is often an"extra" for a graphics format, and some graphics programs will ignore the transparency.Transparent Pixels: One color entry in a single GIF or PNG image’s palette can be defined as"transparent" rather than an actual color. This means that when the decoder encounters a pixelwith this value, it is rendered in the background color of the part of the screen where the image isplaced, also if this varies pixel-by-pixel as in the case of a background image.Applications include:· An image that is not rectangular can be filled to the required rectangle using transparentsurroundings; the image can even have holes (e.g. be ring-shaped)· In a run of text, a special symbol for which an image is used because it is not available in thecharacter set, can be given a transparent background, resulting in a matching background.The transparent color should be chosen carefully, to avoid items that just happen to be the samecolor vanishing.Even this limited form of transparency has patchy implementation, though most popular webbrowsers are capable of displaying transparent GIF images. This support often does not extend toprinting, especially to printing devices which do not include support for transparency in thedevice or driver. Outside the world of web browsers, support is fairly hit-or-miss for transparentGIF files.4. Explain the Domain Name System and DNS servers.The DNS translates Internet domain and host names to IP addresses. DNS automaticallyconverts the names we type in our Web browser address bar to the IP addresses of Webservers hosting those sites.DNS implements a distributed database to store this name andaddress information for all public hosts on the Internet. DNS assumes IP addresses do notchange (are statically assigned rather than dynamically assigned).The DNS database resideson a hierarchy of special database servers. When clients like Web browsers issue requestsinvolving Internet host names, a piece of software called the DNS resolver (usually built intothe network operating system) first contacts a DNS server to determine the servers IPaddress. If the DNS server does not contain the needed mapping, it will in turn forward therequest to a different DNS server at the next higher level in the hierarchy. After potentiallyseveral forwarding and delegation messages are sent within the DNS hierarchy, the IPaddress for the given host eventually arrives at the resolver, that in turn completes therequest over Internet Protocol.DNS additionally includes support for caching requests andfor redundancy. Most network operating systems support configuration of primary,secondary, and tertiary DNS servers, each of which can service initial requests from clients.Internet Service Providers (ISPs) maintain their own DNS servers and use DHCP toautomatically configure clients, relieving most home users of the burden of DNSconfiguration.
5. Explain the use of client-side image maps.Image maps aren’t as bad as they seem, at least if you use a client side image map using HTMLrather than a CGI program. Now you need to put the image on the page. To do this, you use theimage tag, but with a new attribute: usemap.<img src="eximap1.gif" width="200" height="40" border="0" alt="image map"usemap="#mymap" />The usemap="#mymap" command tells the browser to use a map on the page, which is named"mymap". Notice how it uses the "#" symbol in front of the map name. Also notice that wedefined the width and height of the image. This need to be done so we can use coordinates lateron when we define the map. Speaking of that, let’s see how to define the map. For this map, wewould place the following code somewhere on the page.<map name="mymap" id="mymap"><area shape="rect" coords="0, 0, 99, 40" href="table1.htm" alt="Tables" /><area shape="rect" coords="100, 0, 200, 40" href="frame1.htm" alt="Frames" /><area shape="default" href="http://www.pageresource.com" alt="Home" /></map>Now you can see where the usemap="#mymap" from the <img> tag comes from. The name ofthe map is "mymap". Now, let’s look at what all of this means:<map name="mymap" id="mymap">This defines your image map section, and gives the map a name. This map is named "mymap" InXHTML, the id attribute is required rather than name. If you are using XHTML transitional, boththe name and id can be used.<area shape="rect" coords="0,0,99,40" href="table1.htm" alt="Tables" />The area tag defines an area of the image that will be used as a link. The shape attribute tells thebrowser what shape the area will be. To keep it simple, I only used "rect", which stands forrectangle. The coords attribute is where we define the edges of each area. Since it is a rectangle,we will use two sets of coordinates. The first set defines where to start the rectangle, where thetop-left edge of the rectangle will be. Since this rectangle starts at the top-left edge of the image,the coordinates are (0 pixels, 0 pixels). The second two numbers define where to end therectangle. This will be the lower-right edge of the rectangle. Remember that the total image sizewas 200×40. We want the lower-right edge of this rectangle to be halfway across the image andat the bottom of the image. Going across, half of 200 is 100, but we use 99 here because 100 canonly be used once. We will use it in the second rectangle here. Of course, 40 pixels take us to thebottom of the image. So the lower-right corner of this rectangle will be 99 pixels across theimage, and 40 pixels (all the way) down the image. And now the easy part: The href attribute isused to tell the browser where to go when someone clicks someplace on that rectangle. Put the
URL of the page you want to go to in there, and the first rectangle is set up! The alt attributeallows you to define alternate text for that area.<area shape="rect" coords="100, 0, 200, 40" href="frame1.htm" alt="Frames" />Basically the same as the previous area tag, but it is for our second rectangle. We start where theother one left off, but back at the top of the image. Since the right edge of the last rectangle wasat 99 pixels accross, we start this one at 100 pixels accross. And since this will be the upper-leftof the second rectangle, we start it at 0 pixels down the image (the top!). We end this rectanglewhere the image ends, so the lower-right coordinate here is pretty nice- (200, 40), the size of theimage!<area shape="default" href="http://www.pageresource.com"alt= "Home">The default is not really a new shape; it just covers anything that may have been left out. Wedidn’t leave out anything in this map, but if we had, this would be the URL someone would go toif they clicked on any area we did not define earlier.</map>This ends the map section!Now, you can use other shapes besides rectangles, but those are a lot tougher to code by hand.