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Internet proxy and DNS lookup

    Question

  • Hello,

    I am breaking my head to understand the DNS lookup process with Internet proxy enabled with IE. Could some one please help me undesrtand the DNS lookup process with Internet proxy.

    I understand that if I use my proxy PAC file on IE, my browser is using my locally configured DNS server for all internet name resolution and i have confirmed from sniffer.If i use a proxy server specifically by enabling "USE PROXY SERVER FOR YOU LAN" my browser is using proxy server to resolve all internet names.

     

    Is this correct? please advice..

     

    Thank you very much in advance.

     

    sam


    sam
    Wednesday, October 12, 2011 1:06 PM

All replies

  • Hi,

     

    You’re right, if you set a proxy server in IE. All internet access requirement would send to proxy server first. Then proxy server access the destination and return to the client.

     

    A proxy server may optionally alter the client's request or the server's response, and sometimes it may serve the request without contacting the specified server. In this case, it 'caches' responses from the remote server, and returns subsequent requests for the same content directly.


    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. ”
    • Proposed as answer by C-DAB Thursday, July 17, 2014 9:58 AM
    Friday, October 14, 2011 9:43 AM
  • Dear Zen,

    Thank you very much for you response. I looking for the DNS looku procedure while browsing the internet using proxy.

    I understad that all internet request from IE is forwarding to proxy and proxy serving for the IE. But my question is about DNS lookup during this process. Who is resolving the Names in this process ? Local DNS server configured on the client or DNS server confured on the Proxy?

    I hope you understand my concenrn.

     

    Thank you


    sam
    Friday, October 14, 2011 1:22 PM
  • Hi,
    
    Sorry for the delay!
    
    Please refer this article:
    http://support.microsoft.com/kb/172218
    
    The name would be resolved with the DNS server which set on the proxy server only if it could not be found in DNS cache and Host file.
    
    Hope that helps
    


    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. ”
    Thursday, October 20, 2011 9:39 AM
  • Hi,
    
    Sorry for the delay!
    
    Please refer this article:
    http://support.microsoft.com/kb/172218
    
    The name would be resolved with the DNS server which set on the proxy server only if it could not be found in DNS cache and Host file.
    
    Hope that helps
    

    That is incorrect. If a proxy is explicitly defined, the DNS lookup is performed by the proxy and cannot be overridden by the HOSTS file. 

    Friday, October 16, 2015 8:13 PM