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Mui_64918
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Feb 25, 2014

Browser not honoring DNS Anyone faced issues with stuck clients while using GTM

We have an issue when we disable one of the IPs from GTM we still receive traffic to that IP. I have validated that none of the GTM replies with that IP but still some of the clients connect to it even after a week. The TTL is 30 seconds.

 

Anyone else has faced this issue? Its not just few its 100s of clients but 10000s are working correct.

 

7 Replies

  • Yes. With Windows Explorer, it seems that once it does a dns lookup, IE will never again refresh it's cache until all instances of IE (not just the window) are closed out and restarted. I don't know how other bowswers compare.

     

  • I tried with IE7 and IE8 they do honor the DNS response even if they cache it for few mts.

     

  • I tried with IE7 and IE8 they do honor the DNS response even if they cache it for few mts.

     

  • This sounds like more of an issue with some client's local DNS server not honoring your 30 second TTL and caching the response for much longer. Is there any noticable pattern in the IP addresses/ISP of users that are having the issues?

     

  • We are still investigating, from what i see its random users and only common denominator is Firefox 98% and others 2%

     

  • One of my collegues found the bug in firefox https://bugzilla.mozilla.org/show_bug.cgi?id=151929 https://bugzilla.mozilla.org/show_bug.cgi?id=861273

     

    So this is an issue with Firefox 26/27. Hope it gets fixed soon. It is still an open issue, we cannot use GTM with FIREFOX.

     

  • Hi all browsers perform some sort of DNS caching as far as I know, some only for a few seconds. By default most versions of IE cache for 30mins. This can be changed by a registry setting so if someone is seeing no DNS caching for multiple versions of IE I would suggest that your companys SOE may have been modified. The way they behave changes from version to version.

     

    GTM is not a standalone technology to address geo-redundancy and site failover. You must implement other designs to complement GTM ie. BGP failover/ multi-site LTM pools, site-specific redirect. Whatever you do, do not rely on GTM persistence setting for internet users - it will work for approx. 70% of users only and you need another solution to address the remaining 30%. The reason is that you cannot guarantee that a users LDNS will remain constant for the duration of a browser session. Even if your ISP does it right, the next one along won't.

     

    Anyone who uses GTM should read this http://www.tenereillo.com/GSLBPageOfShame.htm to understand - don't be fooled by the name it's great GSLB primer - GTM technology is valid but it's limitations need to be understood by those design solutions around it.