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basic DNS question CNAME

Discussion in 'Network Infrastructure' started by Ence, May 9, 2009.

  1. Ence

    Ence Kilobyte Poster

    Still working on DNS :blink

    So I guess this is basic but I don't understand why I would use an CNAME! whats the point!

    CNAME (Alias) what I have readied is: If I was the type in a web browser CF then certforums.co.uk website would load web page, As I made an CNAME & A record.

    Also read about mapping one host to another host so it has same name. Would I use an CNAME if I hosted two or more website on one server ?

    Is this right. I have looked at wiki and just it just gets more confusing.

    understand what an alias is

    edit: many thanks
  2. JK2447
    Highly Decorated Member Award 500 Likes Award

    JK2447 Petabyte Poster Administrator

    Hi Ence, I'm studying for 291 too. Yeah I think you've got it you know, a CNAME lets multiple services run one the one server, so that they all use different ports but are tied to the one IP address. So like you say, FTP.CERTFORUMS.CO.UK and WWW.CERTFORUMS.CO.UK have the same IP address but as one is HTTP and one is FTP, it will listen in on port 80 for HTTP or 21 for FTP.

    Think thats right . . .

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  3. dales

    dales Terabyte Poster

    think about it this way, if you have a server with IIS on it and it is hosting 2 or more websites hows iis gonna know which one to serve. a Cname record is just a way to give a host record another name as you cannot create 2 host records for the same server/workstation.
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  4. Sparky
    Highly Decorated Member Award

    Sparky Zettabyte Poster Moderator

    I create CNAME records for websites that are hosted on other servers. This means I point the CNAME to the A record of the hosted server. If the company that hosts the server makes any IP address changes I dont have to worry about updating my DNS records. 8)
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