Pinging websites and MTU size

Discussion in 'Internet Explorer' started by Tony Williams, Feb 14, 2008.

  1. There are a couple of sites that I have problems visiting using IE 7. They
    are and
    I was told by Tesco to lower the MTU to 1400 on my router but this hasn't
    helped. I have no problems with the sites on Opera. The strange thing is
    that if I try to ping these sites from the CMD screen I get a timed out
    reply. If I try and ping any other sites I get a response. can anyone
    suggest why this happens?
    Tony Williams, Feb 14, 2008
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  2. PA Bear [MS MVP], Feb 14, 2008
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  3. Thanks for the tip. Tried it and didn't show any errors suggested up MTU to
    1500 but I'm on ADSL and I think the max should be 1492?
    Tony Williams, Feb 14, 2008
  4. PA Bear [MS MVP], Feb 14, 2008

  5. Obviously those sites (or servers on the path to them) block ICMP.
    Unfortunately the value of ping and tracert as diagnostics has been
    greatly reduced as servers have taken defensive measures against
    moronic "Denial Of Service exploits".

    However, you might still be able to check if you have an MTU size problem
    with a site by using tracert to find out where the ICMP starts being blocked.
    Then just do the ping -f -l to the last server you do reach. Otherwise, you
    will just have to use some other protocol than ICMP to do your tests with.

    Good luck

    Robert Aldwinckle
    Robert Aldwinckle, Feb 14, 2008
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