ampr.org subdomains - 44net

17 Apr 2014

An open question on ampr.org hostnames (see my response below):

On 2014-04-08 15:32, Brian Kantor wrote:
...
  Dean, I feel it would be a bad idea to delegate the
forward lookup to your nameserver without also delegating the reverse lookup, which would
be difficult and we do not do.  You can continue to have as many names in the ampr.org dns
like ns1.ae7q as you like by having John set them up for you, which will automatically set
up the appropriate PTR record as well.  I'd much rather you did it this way.

 Best wishes. - Brian

 On 2014-04-04 17:47, Dean Gibson wrote (to&lt;bkantor(a)ucsd.ude&gt;)e>):
>> I have IP address 44.24.240.173 in Bart Kus’s 44.24.240.0/20 block.  I sent a
request to John Hays, the admin for the 44.24.0.0/16 block to add the following records to
the ampr.org domain:
>> ns1.ae7q   IN   A   44.24.240.173
>> ae7q   IN   NS   ns1.ae7q
>> This would allow me to create additional hostnames in the ae7q.ampr.org
sub-domain, in my own DNS server.  I’ve run BIND for 15 years, and this is a nice way to
delegate a sub-domain;  the ampr.org domain remains protected.
>> John was able to add the first line to the domain, but not the second line, and
he suggested that I contact you.  I see other NS records in the ampr.org domain;  is this
something that you can do?
>> Sincerely, Dean AE7Q
>> 

I understand the difficulty with delegating the reverse lookup in 
general, which I was not requesting and don't need.  It's often not done 
on the Internet anyway for small (eg, hobby) servers, except for mail 
servers, where it is a means of spam server detection. I've run multiple 
sites with various functions (DNS, mail, web) on one box on the Internet 
for 15+ years, and the only reverse DNS I've ever needed was for mail 
servers.

Usually, a hobby machine serves several functions within the same box, 
and multiple hostnames are mapped to the same IP address.  In fact, for 
ae7q.com (and my other domains), due to DNS requirements, I can't use 
CNAMEs for the domain hostname (for those that leave off www.), the 
nameserver hostname, or the mail server hostname (NS and MX records 
can't reference a CNAME -- RFC 2181 
<https://tools.ietf.org/html/rfc2181> section 10.3).  These all use an 
"A" record to assign the *same IP address* as the mail server (which 
also can't use a CNAME, due to spam detection).  That's three "A" 
records to one IP address (and that's just in one domain), and it is a 
very common practice.  I do use CNAMEs other places.

I understand that you would like a PTR record for every hostname, but 
that has the following negative consequences that I can see:

 1. It encourages people to request a larger IP address block than they
    need, and then create a multi-homed machine for the various
    functions.  I think it's a really bad idea to consume unnecessary IP
    addresses, and I think it's already happening in the 44.x.x.x network.
 2. For frequent changes, it unfairly and unduly burdens those
    volunteers who have to respond to requests.  I make *very* frequent
    changes to my Internet and LAN domain records.  I have over 50
    network devices on my LAN at home on five subdomains, and I use DDNS
    (both manually and via DHCP) for most of them (it's just easier than
    changing a zone file and restarting BIND).  Granted, most of those
    won't be on the 44.x.x.x network, but the present scheme discourages
    experimenting with configurations by amateurs who don't want to
    burden the volunteers who make the ampr.org changes.

I would suggest that you reconsider your position of requiring a PTR 
record for each hostname.

Much better to have a policy of encouraging *user-managed* subdomains, 
in my opinion;  that would help lead to a consistency in hostnames in 
ampr.org (eg, all of the form <whatever>.<callsign>.ampr.org).  A much 
poorer alternative (also my opinion) is the present practice of having 
end users to *submit to coordinators* CNAME records for subdomains of 
any "A" records that are allocated to them.

Frankly, the former suggestion (user-managed subdomains where an 
ampr.org coordinator adds the "NS" record *once*), is a lot less work, 
in my opinion.  Or is there a risk I'm not aware of? Remember, the 
subdomains are served off of the user's DNS server(s), not the ampr.org 
DNS servers.

Sincerely, Dean Gibson AE7Q