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DNS Lookup

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  • DNS Lookup


    What is DNS?

    DNS is stand for Domain Name System (or Service or Server), an Internet service that translates domain names into IP addresses. Because domain names are alphabetic, they are easier to remember. The Internet however, is really based on IP addresses. Every time you use a domain name, therefore, a DNS service must translate the name into the corresponding IP address. For example, the domain name http://www.example.com might translate to 10.0.154.2


    Hardware
    • PHPoC Blue (+ USB WLAN) or PHPoC Black (+ Ethernet cable)
    • Micro USB to USB Cable (to upload source code to PHPoC Device)


    Quick Steps

    Source code of this example is a part of PHPoC Support Packet (PSP). You need to:
    • Download PHPoC Support Package.
    • Upload example\net\01.php_task\dns_lookup to PHPoC Blue/Black.
    • Modify the Domain Name as you want in task0.php
    • Save the modified file.
    • Configure network parameters (e.g. WiFi SSID, password, IP address ...).
    If you use PHPoC for the first time, see How To Use PSP.


    Source Code

    Source files includes:
    • init.php: this file is run when PHPoC system is powered or reset. It is used to specify which file is run is system loop.
    • task0.php: this file is run in system loop of PHPoC devices.

    init.php

    This file is run when PHPoC system is powered or reset. It is used to specify that task0.php is run is system loop.
    PHP Code:
    <?php

    system
    ("php task0.php");

    ?>



    task0.php

    [Full Code]
    PHP Code:
    <?php

    if(_SERVER("REQUEST_METHOD"))
     exit; 
    // avoid php execution via http request

    include_once "/lib/sn_dns.php";

    echo 
    "PHPoC example : get ip address by host name\r\n";

    dns_setup(0"");

    $host_name "www.google.com";
    $host_addr dns_lookup($host_nameRR_A);

    if(
    $host_addr == $host_name)
     echo 
    "$host_name : Not Found\r\n";
    else
     echo 
    "$host_name : $host_addr\r\n";

    ?>



    [Explanation]

    Source code of this file does:
    • Perform DNS lookup to translate domain names of TCP server into IP addresses.
    • Print hostname and IP address to PHPoC debugger console.


    Test and Result
    • Click "Run" button on PHPoC Debugger.
    • See Result on PHPoC Debugger's Console.


    See Also

    Other Resources
    Last edited by support; 02-09-2018, 09:40 AM.
      Posting comments is disabled.

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