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it would be $ORIGIN 113.168.192.IN-ADDR.ARPA. for a netmask

but what would the origin be for a netmask of

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up vote 2 down vote accepted

If I understood you correctly, you are looking to create a reverse DNS allocation for /17 with one $ORIGIN, thats not possible and for allocations larger than a /24 block you would have to breakdown your /17 into 128 sets of /24 and use individual sets for reverse DNS.

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there are other ways of doing this (e.g. with CNAMEs), but this is pretty much the easiest. – Alnitak Nov 4 '11 at 11:38
do i need $ORIGIN at all? – The Digital Ninja Nov 4 '11 at 11:46
@Alnitak, but still one would be required to be put a PTR record somewhere right, or did I get it wrong ? $ORIGIN is to append whatever comes after it ($ORIGIN) to your individual records, so yes put it, saves you some typing. – Gaumire Nov 4 '11 at 11:53
I guess a better question would be what is the simplest way to add reverse dns for all my virtual machines? I have it set up with a split horizon dns and want the local ips to resolve to names. I dont want to have to create 128 files. – The Digital Ninja Nov 4 '11 at 12:12
@Gaurmire I was talking about RFC 2317 - – Alnitak Nov 4 '11 at 13:04

The reverse DNS has nothing to do with a netmask. It is just the PTR of an IP.

So the answer is: The same!

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