[Ilugc] Single DNS for multiple IP address
- From: binand@xxxxxxxxx (Binand Sethumadhavan)
- Date: Thu Apr 13 17:26:58 2006
On 13/04/06, R.Subramanian (RS) <rs2003@xxxxxxxxx> wrote:
On 4/13/06, Binand Sethumadhavan <binand@xxxxxxxxx> wrote:
For the low investment type people, there isn't much of a solution to
this problem except ensuring that your link does not go down.
No. We are running servers on low cost lines.
With two different ips.
The procedure varies and depends on what is connected to the ip. ( mail
server / webserver / vpn database etc)
I did read your response in this thread. Let me explain to you the
flaw of that approach.
Say you have www.foo.com with two IPs, IP1 and IP2. You add those in
the authoritative DNS server for foo.com as:
www.foo.com. 86400 IN A IP1
www.foo.com. 86400 IN A IP2
Now, there is nothing in the RFCs that tells the clients to try these
IPs in any set order, or something that forces them to try all these
IPs. So, you can expect roughly half your clients to connect over IP1
and the other half to connect over IP2. Now you can see that when your
IP1 is down, half your clients will not be able to connect to your
webserver. They wouldn't try the other IP as DNS responses are cached.
Binand
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