[mythtv-users] Re: Why only numeric IP addresses work?

IvanK. chepati at yahoo.com
Wed Oct 13 21:57:29 UTC 2004

On Wednesday 13 October 2004 03:49 pm, Joseph A. Caputo wrote:

> *********
> DISCLAIMER:  The following is a very high-level description DNS &
> routing; none of this should be considered gospel, nor should I in any
> way be mistaken for a networking expert.  The purpose is only to
> illustrate why DynDNS doesn't care where your packets should be routed.
> *********
> DynDNS doesn't do *routing*.  It provides DNS (Dynamic Name Services).
> On a very simple level (they have other services, too) all it does is
> map a hostname to an IP address.  If I query my primary DNS server for
> the IP address assigned to the hostname "foobar.dyndns.org", it will
> query the master DNS server for the dyndns.org domain, which will tell
> it the IP address is, say,  My primary DNS server will
> then return that address to the application on my box that requested
> it, at which point that application can continue whatever network
> operation it wants to do.  All packets going out of my box will have a
> destination IP address (or possibly a multicast or broadcast address,
> but NOT a hostname) in the header.  When it hits my router, my router
> will know that is an internal address and route the packet
> appropriately.

This is the stupidest use of dyndns I've ever heard of and people who do this 
should be denied internet access for a month :-)

That's like taking the free communal bus to go from your porch to your 
backyard, cause you're too lazy to walk across the house.  And it takes you 
longer too, but I'd say you deserve this.

Is the overhead incurred in doing dns queries worth the effort you save by not 
including an entry in your hosts file???

Sheesh...  I'm using hn.org (a dyndns equivalent) and I'd hate to see people 
tieing resources for local dns queries.

Joseph, this is not meant as a critique of you, but people who'd use dyndns 
for that purpose.

> So, while it may not be proper netiquette to register a
> globally-resolvable host/domain name with an internal IP address, there
> is no technical reason it can't be done if your main objective is to
> provide yourself with DNS services for your internal network without
> going to the trouble of setting up your own DNS server.

I knew a disclaimer was coming :-)

> Of course, the drawback to this approach is that if your Internet
> connection ever goes away, or if DynDNS has an interruption in service
> you won't be able to resolve any hostnames in your internal network...

Serves them right.


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