[TriLUG] Slides from last night's DNS Presentation

[Matt Pusateri]

On Fri, October 15, 2004 11:08 am, Aaron S. Joyner said:
> Matt Pusateri wrote:

<snip>

>>It might be worth explaining what lame servers are as those new to
>> DNS
>>will most likely see them in their DNS logs and might wonder what
>> they
>>are.
>>
>>
> A lame server, comes from a lame delegation.  It's not (usually) the
> fault of the server being blamed, but of the zone that points to it.
> Consider this scenario:
> - You run the zone, example.com
> - You configure your zone file to have 3 NS records, ns1.example.com,
> ns2.example.com, and ns3.example.com
> - You point these 3 NS records at 3 different servers, 1.2.3.2,
> 1.2.3.3,
> and 1.2.3.4
> - You configure 1.2.3.2 and 1.2.3.3, but forget to configure 1.2.3.4
>
> At this point, 1.2.3.4 is a "lame server", because if you ask it for
> example.com, it will give a non-authoritative response, if any.  The
> more common scenario (and this is a real example from TriLUG's recent
> history), is where that "lame server" *USED* to be a valid DNS server,
> but has since been reformatted or reworked, and is no longer
> configured.  We had old NS records left over from when certain
> individuals used to be backup slave servers for the trilug.org domain.
> This caused some confusion, and if you search you can probably find a
> history of it on the list.
>
> Sorry for being slow in the response.  :)
>
> Aaron S. Joyner

First, don't be sorry we all have real jobs to do that for whatever
reason have to take priority (at least that's what my boss thinks :)

Second,  Wouldn't it also be possible for a server to be lame due to a
valid DNS change that hasn't propagated through to all name servers
yet.  For example, you make a request to your ISP name server since
you are using it as a forwarder.  They have example.com cached so they
give you the NS from their cache.  Unfortunately example.com just made
a network change either changed ISP's or servers or whatever so the
information that your ISP had cached is no longer accurate.  Hopefully
example.com wouldn't get rid of their old name server until the new
one propageted, but I could see how some sites due to resources or
politics wouldn't have that choice. Or have I missed something here.