Class C delegation, am I doing this correctly?

Ray Van Dolson rayvd at
Sat Nov 19 01:10:24 UTC 2005

We have a /19 reallocated to us from Sprint.

Of that, I would like to delegate reverse DNS authority for a /24 to
another ISP's nameserver's.

Using the REASSIGN forms on ARIN do not work--complains about not being
a /16.

Apparently our ISP (Sprint) is therefore delegating 8 /24's to us
individually since we are only receiving a /19 from them.  So to
delegate a /24 from that to our customer ISP I am doing the following:

$TTL 86400      ; max TTL

@       IN      SOA (
                                2005111836      ;       Serial
                                28800           ;       Refresh
                                7200            ;       Retry
                                604800          ;       Expire
                                3600 )          ;       TTL Minimum
@               IN      NS
@               IN      NS

$GENERATE 1-255 $      NS      NS01.ISP.COM.
$GENERATE 1-255 $      NS      NS02.ISP.COM.
$GENERATE 1-255 $      NS      NS03.ISP.COM.
$GENERATE 1-255 $      NS      NS04.ISP.COM.

(IP's changed to protect the guilty)

This seems to work with a couple oddities:

Automatic AXFR's of the zone with the GENERATE macro run does not
appear to move over to (my secondary nameserver).
I am doing a dig @ns1 axfr > zonefile on to bring the zonefile over.  The GENERATE macro is
expanded correctly here.

Reverse DNS resolution from out on the internet of one of these IP's
still doesn't appear to work.  No valid IP is returned.  Maybe this is
a propagation issue, so I will give it a day.

Using dnstracer -s . -c -C -o -4 shows the
NS01.ISP.COM, etc nameservers under ours, so at least that appears to
be working correctly.

Thanks for pointing out any problems.

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