Primary & Secondary DNS

bryan

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Aug 5, 2003
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I had hoped that I could host my website on 2 different servers where the primary DNS is used for the first "copy" and the secondary for the second. If for some reason, the first host fails, the secondary would take the traffic.
That's how I would have designed it - why else have a secondary?

Is there someone out there that would comment?
 

murraybiscuit

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Oct 10, 2008
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secondary dns is a failover for name to ip address resolution.
it's the next step up in the redundancy chain. you're thinking too low down.
the point of the net is that if one node goes down, another node can tell you how to find the data on another node.
if redundancy at a site-level is your problem, back up your data on another server and restore it if need be.
mirroring and cdn is primarily for load-balancing requests based on geography and has a spin-off of redundancy.

what if you had 5 nameservers and 4 of them went down?
surely you wouldn't have a mirror on every single server? that's horribly inefficient for the needs of most websites.
look, if hardware went down and servers failed every couple of days, you may have a point.
it's just not optimal, considering server failure is uncommon, and things like raid and cloud add an extra layer to redundancy.
 
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bryan

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Aug 5, 2003
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Thks so much - your helpful reply. If I host my website on a server in SA and also have a "copy" on a server in USA - if the SA server fails (for whatever reason), would visitors be served by the US server - the URL is "pointed" at both? via the two DNS entries
 

RSkeens

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Thks so much - your helpful reply. If I host my website on a server in SA and also have a "copy" on a server in USA - if the SA server fails (for whatever reason), would visitors be served by the US server - the URL is "pointed" at both? via the two DNS entries

That can easily be achieved, as long as there is DNS failover set up (many third party DNS providers offer this). An alternative is to even have it manually changed in times of trouble.

As to your original post, the entire point of secondary DNS servers is for redundancy and load balancing. It's always best to host your DNS servers on different machines.
 

bryan

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Aug 5, 2003
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wow - really know your stuff - hopefully u can help with even more info - how can I set my hosting that a website in USA serves visitors from USA and website is SA serves SA visitors - is there sniffer code out there with code to achieve this?
 

RSkeens

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wow - really know your stuff - hopefully u can help with even more info - how can I set my hosting that a website in USA serves visitors from USA and website is SA serves SA visitors - is there sniffer code out there with code to achieve this?

The way to accomplish this would be to set up the name servers in a split - horizon configuration.
 
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