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Is there a way to localize dns entries? Meaning, that users from asia resolve to another ip than users from usa or europe. This would be helpful to give the users the server nearby. DNS is the only technique used so far, meaning I cannot place some softwarerouting or central system replacing the dns to solve this.

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2 Answers 2

up vote 12 down vote accepted

Yes, there are currently two popular solutions to this problem.

The first is called Anycast, where the same IP block is literally in use in multiple locations around the world. That is to say, the name servers for your domain always return the same IP address, but that IP address is actually assigned to more than one set of physical servers.

You can read more about it here

The second technique again involves AnyCast, however this time, the IP address range being anycasted referes to our name servers themselves. As the nameservers will only requests from clients who they are closest too (as determined by the magic of BGP), they can themselves return IP addresses that are logically local to the client.

An example of this is google's domain

From a host in Australia

crimson:~ dave$ host is an alias for is an alias for has address has address has address has address

From a host in the US

[dave@odessa ~]$ host is an alias for has address has address has address has address has address has address

So, the CNAME for resolves to, but when you resolve that, depending on your location, your client receives a different set of IP addresses. This is because the name server that received the request for was the local nameserver, relative to the client.

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This answer technically addresses the question, but I think it is rather useless in terms of being a real answer for an actual problem: most parties don't have anycast, so your answer is out of reach for all such parties. – cnst Mar 21 '13 at 1:27
so which registrant offer this solution? – dynamic Nov 7 '13 at 0:21
Also worth noting that DNS has this feature natively. Put a DNS server in a region with a record pointing to a webserver in that region. Repeat in other regions. Profit. – dmourati Jan 22 at 8:16

If you only want to localise servers for Asia, North America and Europe, then you could decide to run both your webapp and your DNS yourself.

With DNS, you could use something like the Split-Horizon DNS approach, which could either be achieved through integrated functionality of your DNS server (they may call it GeoDNS), or through a firewall that would redirect different IP-address ranges to different running instances of your DNS server (you could run several different copies of the server on your local machine, which will listen at different local IP-addresses).

You could probably get expected results in ≈90% of cases by replying to DNS requests from RIPE and AfriNIC IP-addresses with an A record of your host in Europe, requests from APNIC — host in Asia, and requests from the IP-addresses from the /8 blocks administered by ARIN, LACNIC and the rest of the /8 address space with an A record of your server in North America. This will have some wrong results in certain situations (some /8 blocks are shared between Europe and North America, some address space is anycast etc), but the worst that would happen is some extra latency to the affected party, so, it shouldn't be a big deal.

(And, yes, there should be a way to make these things easier, but, so far, it seems like there is none.)

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