IExplorer cannot see websites with ICMP turned off

Posted on 2009-02-09
Last Modified: 2013-12-08
I have 4 computers on our network that can't go to websites such as, but can go to  Upon further investigation, these PC's can only go to sites that still have ICMP turned on.  I can load Firefox and it works fine, but I really need to get Explorer working as it's the only browser authorized by our company. I reset all security and Explorer parameters to default and even turned off the firewall and tried turning off ALL security options in IE. THe 404 error is what comes up.  There are 50 or so computers on the network, and so far, only four are affected. I've also run spyware and antivirus scans and turned up nothing.  
Question by:n7okn
    LVL 97

    Assisted Solution

    Hello n7okn,

    Do you have a group policy blocking websites without ICMP?  Add the websites to your trusted zone.

    1. Clear your DNS cache.  Go to Start > Run and type CMD
    and hit OK.
    At the command prompt, type ipconfig /flushDNS
    and hit OK.

    2. Clear your cache.  Go to Tools > Internet Options > General tab.  Under Temporary Internet Files, click "Delete Files" button. Also click "Delete Cookies" button. Click OK.

    3. Reset the Maximum Transmission Unit in the registry

    4. If no joy, check if your PC is blocking the site.  Do a search for HOSTS file and open it with an editor like Notepad. Delete any line that has the blocked site in it.

    HOSTS file is located in
    Windows XP      =      C:\WINDOWS\SYSTEM32\DRIVERS\ETC
    Windows 2K     =     C:\WINNT\SYSTEM32\DRIVERS\ETC
    Win 98/ME     =     C:\WINDOWS

    It is a hidden file. Go to any folder and select Tools > Folders Options > View. Check "Show hidden files and folders". Click OK.

    5a. If you are using Internet Explorer, check if the site is restricted or blocked.  Go to Tools > Internet Options > Security. Highlight Restricted Sites and see if the blocked site is located there.

    5b. Also under Content tab > Content Advisor, check if the site is restricted there. Remove it.

    5c. Also, under Security tab, add the website to your trusted zone.

    6. Check if antispyware, antivirus, or firewall is blocking the website. Disable these programs one by one.

    Hope this helps!
    LVL 3

    Author Comment

    OK well DNS isn't the issue because a ping returns the address. THis would rule out a hosts issue or the PC blocking the site. There are no policies requiring ICMP to work for websites to be viewed.  I played with MTU to no avail. I can telnet to these websites by name using port 80 and get HTML in the session.  They are running IE7 with XPSP3.  No content advisor is running on these machines. We are using a DNS based content filter on the DNS server, and since we can clearly see the website by name in telnet port 80, the problem is not content filter related. It's got to be Internet Explorer. I have not reloaded IE7, but I guess that's the next step unless someone out there has seen this before.
    LVL 3

    Accepted Solution

    I reloaded IE and that solved the problem.

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