On 5/29/15 12:42 PM, Pedja YT9TP wrote:
I am not quite clear what you mean as subdomain.
Can you point out of some sample of domain usage which is not subdomain?
Pedja YT9TP
Here is a non-subdomained address:
*aa6hf.ampr.org*
Name: aa6hf.ampr.org Address: 44.17.0.128 aa6hf.ampr.org mail exchanger = 10 aa6hf.ampr.org. aa6hf.ampr.org mail exchanger = 20 linux.aa6hf.ampr.org.
Authoritative answers can be found from: *ampr.org nameserver = hamradio.ucsd.edu.* ampr.org nameserver = munnari.OZ.AU. ampr.org nameserver = ns1.defaultroute.net. ampr.org nameserver = ns0.comgw.net. ampr.org nameserver = ns2.threshinc.com. ampr.org nameserver = ampr.org. ampr.org nameserver = ampr-dns.in-berlin.de.
ampr.org internet address = 44.0.0.1
It is not a subdomain, it's address is served by the ampr.org nameservers.
Here is a delegated subdomain (some lines removed for more clarity and less clutter):
*de.ampr.org*
de.ampr.org text = "de.ampr.org - Seit 2012-03-17 im Testbetrieb. hamradio.ucsd.edu *delegated*" de.ampr.org mail exchanger = 20 kle.nw.schule.de. de.ampr.org origin = de.ampr.org mail addr = ipkoord.de.ampr.org
Name: de.ampr.org Address: 134.91.19.148 *de.ampr.org nameserver = db0res.ampr.org.* de.ampr.org nameserver = db0fhn.efi.fh-nuernberg.de. de.ampr.org nameserver = ns.db0fhn.ampr.org. de.ampr.org nameserver = db0res.de.
It is a subdomain because it is being served by de.ampr.org name servers, not ampr.org. No x.de.ampr.org addresses are served by ampr.org. This can be further subdomained, as many times as needed.
Subdomaining hands off (delegates) the responsibility for a namespace (e.g., de.amp.org) or a range of IP addresses (e.g., 44.130/16, meaning 44.130.0.0 through 44.130.255.255) to another entity and nameserver(s).
The advantage of a delegated subdomain is that you can update your subdomain's DNS records without having to get someone else to do it.
The disadvantage is that someone must install, maintain, and operate a DNS server. I do this for my own (non-ham) domains, but I've had decades of experience with DNS servers (I have been working with the Internet since before DNS was created, ALL of the hosts that were public were listed in a single file and installed on every host! :-), not everyone wants to go to that effort.
I'm just getting back into Packet Radio and the 44 net after a decade and a half dedicated to work and family, and I'm still learning how things have been put together in the intervening years.
- Richard, VE7CVS