Dynamic IP

Re: Dynamic IP

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At 8:33 PM -0800 11/8/04, Scott Haneda wrote:
>on 11/8/04 8:17 PM, Men & Mice Support at cbuxton@menandmice.com wrote:
>
>> A dynamic DNS client should be available from whatever dynamic DNS
>> system your friend chooses to use. However, if you're talking about
>> him hitting your web server periodically, then it's not really
>> necessary.
>>
>> So I'd guess you're asking about nsupdate. You can use something like this:
>>
>> nsupdate -k /var/named/conf/user_before data
>>
>> where data is a return-separated list of statements. If you want to
>> just replace the A record named "example.com" with a new one each
>> time, you can use statements like this:
>>
>> zone example.com
>> update delete example.com A
>> update add example.com 900 A ip-addr
>> send
>>
>> The "900" is a TTL of 15 minutes. Replace "ip-addr" with the new IP address.
>
>Perfect, and I don't have to tell bind anything special in re to dynamic
>zones? It knows to reload the zone with the use of nsupdate?

You have to set the zone to be dynamic. QuickDNS will set the
security so that only the key defined in /var/named/conf/user_before
can be used to sign updates. (If you want to create another key, it
can be done.)

The great thing about dynamic updates is, named doesn't have to
reload the entire zone. It just makes changes to the copy of the zone
it has in memory. It also saves these to a journal file, which it
merges into the actual zone file once every so often.

Of course, this means that once a zone is set to be dynamic, all
edits must be made through dynamic updates. QuickDNS understands this
and will make all changes that way, rather than directly altering the
zone file. The only catch is, if you have zone transfers restricted,
you must make sure that the localhost address (127.0.0.1) is
permitted to get zone transfers.

>To confirm
>nsupdate -k /var/named/conf/user_before data.txt
>
>Cat data.txt
>zone example.com
>update delete example.com A
>update add example.com 900 A ip-addr
>send

Yes, that's correct.

Chris Buxton
Men & Mice - Making DNS Easy
Customer Service and Sales Engineer

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