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First of all, I'm not that into DNS, so maybe the answer to this question is very obvious, sorry in either way.

What I want is this: A DNS record which catches all non-existing subdomains on my site and link them to the external address of my site.

So, not to my internal IP address, but to my external hostname. I'm using CloudFlare and want to hide my server IP to the public, by setting it behind CloudFlare. When doing a ping then brings the IP of CloudFlare.

Examples:

www.example.com                  -> www.example.com
existing-subdomain.example.com   -> existing-subdomain.example.com
non-existing-sub.example.com     -> www.example.com (and NOT the internal IP)

So then when somebody tries to fetch the IP with tracert or http://www.hcidata.info/host2ip.cgi for example they would not get to see my IP.

It doesn't necessarily have to link to my homepage, I would be very happy if there's just no way to see my server IP via such non-existing subdomains.

Thanks in advance

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1 Answer

up vote 1 down vote accepted

If you are use BIND or similar dns server:

In your dns, create an A record as follow

*    IN    A    < External IP >

If your external IP is 1.2.3.4, the line will be EXACTLY as follow

*    IN    A    1.2.3.4

If you want to point to a hostname, use following (remember to put period/dot '.' at the end of the complete hostname)

*    IN    CNAME    www.google.com.

The DNS server will reply with that IP address for all undefined host/sub-domain.

If you are using Windows dns server

Create a host record with hostname '*' and the external IP.

PS: Though the above do achieve what you want, in normal situation, a dns query to a non-exist host/sub-domain should not return any IP address.

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Hmm, but can it also be an external address/hostname like www.google.com? And by the way, what should I have configured wrongly if I can access non-existing subdomains? I would also be happy if you just couldn't access them. –  Martin Nov 7 '12 at 7:25
    
I updated the answer if you want to point to a hostname instead of IP. If you actually don't want people to reach non-exist hostname, you don't have to do anything (no need to add those * line). –  John Siu Nov 7 '12 at 7:36
    
Great! Thanks a lot, John! I'd love to upvote you, but I can't yet. –  Martin Nov 7 '12 at 7:37
    
No problem, you can do tomorrow, LOL. Later. –  John Siu Nov 7 '12 at 7:38
    
Haha, will do. Also, "If you actually don't want people to reach non-exist hostname, you don't have to do anything (no need to add those * line)", I have that right now, but people can still reach non-existing subdomains. Perhaps it has something to do with CloudFlare? –  Martin Nov 7 '12 at 7:40
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