What qualfies a namespace?
xiaoxia2005a at yahoo.com
Sat Oct 21 00:37:50 UTC 2006
Edward Lewis wrote:
> At 4:50 -0700 10/20/06, April wrote:
> >Is a root a must have?
> >Without a root, I may call a second level dormain (when there is a
> >root) my top domain, is there anything wrong with it?
> I love esoteric questions in the morning...they smell like, like, a
> whole day's worth of work. (see
> http://news.bbc.co.uk/2/hi/entertainment/3362603.stm "I love the
> smell of napalm in the morning." ... "Smelled like... victory.")
> A "name space" is a generic concept - a set of name and operators
> defining relationships among them. But I don't think that is what
> you want to know.
> (As said in "Airplane" - "But that's not important now.")
> There are a few answers that do apply to your question.
> When talking about the DNS protocol, which is basically a
> query/response, client/server protocol, when you ask a question, the
> answer you get back depends on how the server is configured. If you
> ask a question that a server has the answer for, then hierarchy,
> i.e., having a root, is unimportant.
> Then talking about the DNS as a system, having a root is a really
> good idea. You can have a bunch of domains on a set of core servers
> without ever configuring a root zone. It can work. But maintaining
> such a configuration will be very expensive, and hard to train new
> staff to understand.
> Each client (recurser, stub, resolver, call them what you want) needs
> a fall-back place to send queries when it doesn't know what to do.
> For a client that is willing to walk the tree (i.e., iterate), it
> wants to know where to begin - that is - where's the start or root in
> DNS terminology of the name space?
> The servers listed could have a root zone (".") or they could all
> have a consistent set of other zones from which the name space can be
> walked down. (The DNS name space is organized as a tree, name spaces
> in general need not be.)
> Here's an example of why you want to have a root zone in DNS. Let's
> say you have 5 core servers and you have 4 domains that folks want to
> get data from. Let's say the domains are "red." "blue."
> "green.color." and "voip.sip.ietf." Without a root zone, you have to
> have all four of these zones on all 5 servers. Note that they don't
> all need to be "TLD" (one label), or that TLD can refer to any domain
> with no parent.
> (TLD usually means a domain with one label, like "com.", "net.",
> "org.", but the issues surrounding them also apply to "co.uk.",
> "193.in-addr.arpa." and don't generally apply to arpa.)
> Now you want to add "purple." as a new domain. You have to configure
> "purple." on all 5 servers. You would have to modify the 5
> named.conf's to carry "purple." everywhere. This takes some time,
> and more importantly, if not done swiftly could cause some disruption
> as the change is rolled out.
> Had there been a root zone on the 5 core machines, then you could set
> up servers for "purple." on any machines you want, the number being
> dependent on the need. After testing that "purple." servers are up
> and running, you would then put the delegations into the root zone
> and use your zone propagation system (AXFR, rsync or something else)
> to send out updates. This approach is smooth as you can first test
> the servers (for "purple.") and then in one command update the live
> root zone. Propagation of the root zone, if designed well, will be
> fast, faster than manually ssh'ing into all the servers, updating
> named.conf (which you would also want to source control...) and
> reconfig'ing (you would not want to reboot the process) the servers.
> Imagine if you made a typo and the config failed.
> DNS is designed to have a root zone. It doesn't need one, but
> without it, the cost of operating a DNS system is higher than not.
> Note that I said "a root" zone. There are non-technical debates over
> "the root" zone that is published by IANA/ICANN. That's not a topic
> for this list.
> Edward Lewis +1-571-434-5468
> Secrets of Success #107: Why arrive at 7am for the good parking space?
> Come in at 11am while the early birds drive out to lunch.
Thanks Edward for your time and efforts ...
In the example, I think if we use forward, in addition to delegation,
you can still get by, even without a root.
In such a no root environment, do we still call it a namespace, or
directly call the individual domains?
Then if I only have son.father and grandson.son.father two domains, can
I refer them to my top domain and my subdomain. As I do not have a
root, so I can care less about the absolute levels from the root, if it
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