How to force DNS refresh for a website

Question

I m moving my web application to another server and in the next few days I ll refresh the DNS to point to the new IP location   Unfortunately some browsers and SOs keep a DNS cache that will make users point to the old IP location  Some users are rookies and they ll not refresh the DNS cache manually and I know we ll lose a lot of them in the first weeks after this change   Is there anyway to force this DNS cache to refresh so it ll be transparent for our final users

User · Answer

you can t force refresh but you can forward all old ip requests to new one  for a website   replace  OLD IP  with old server s ip   replace  NEW IP  with new server s ip  run  amp  win   echo  1     proc sys net ipv4 ip forward  iptables -t nat -A PREROUTING -d  OLD IP  -p tcp --dport 80 -j DNAT --to-destination  NEW IP  80  iptables -t nat -A PREROUTING -d  OLD IP  -p tcp --dport 443 -j DNAT --to-destination  NEW IP  443  iptables -t nat -A POSTROUTING -j MASQUERADE

User · Answer

As far as I know  a forced update like this is not directly possible  You might be able to reduce the DNS downtime by reducing the TTL  Time-To-Live  value of the entries before changing them  if your name server service provider allows that   Here s a guide for less painful DNS changes   A fair warning  though - not all name servers between your client and the authoritative  origin  name server will enforce your TTL  they might have their own caching time

User · Answer

If both of your servers are using WHM  I think we can reduce the time to nil  Create your domain in the new server and set everything ready  Go to the previous server and delete the account corresponding to that domain  Until now I have got no errors by doing this and felt the update instantaneous  FYI I used hostgator hosting  both dedicated servers   And I really dont know why it is so  It s supposed to be not like that until the TTL is over

User · Answer

It might be possible to delete the Zone Record entirely  then recreate it exactly as you want it  Perhaps this will force a full propagation  If I m wrong  somebody tell me and I ll delete this suggestion  Also  I don t know how to save a Zone Record and recreate it using WHM or any other tool   I do know that when I deleted a hosting account today and recreated it  the original Zone Record seemed to be propagated instantly to a DNS resolver up the line from my computer  That is good evidence it works

User · Answer

There s no guaranteed way to force the user to clear the DNS cache  and it is often done by their ISP on top of their OS  It shouldn t take more than 24 hours for the updated DNS to propagate  Your best option is to make the transition seamless to the user by using something like mod proxy with Apache to create a reverse proxy to your new server  That would cause all queries to the old server to still return the proper results and after a few days you would be free to remove the reverse proxy

User · Answer

So if the issue is you just created a website and your clients or any given ISP DNS is cached and doesn t show new site yet  Yes all the other stuff applies ipconfig reset browser etc  BUT here s an Idea and something I do from time to time  You can set an alternate network ISP s DNS in the tcpip properties on the NIC properties  So if your ISP is say telstra and it hasn t propagated or updated you can specify an alternate service providers dns there  if that isp dns is updated before your native one hey presto you will see new site But there is lots of other tricks you can do to determine propagation and get mail to work prior to the DNS updating  drop me a line if any one wants to chat

[caching] How to force DNS refresh for a website?

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