Re: Some thoughts/comments on draft-gont-6man-slaac-dns-config-issues-01

[Mark Andrews <[e-mail]>]

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To: Fernando Gont <[e-mail]>
Cc: Mark ZZZ Smith <[e-mail]>,
    "[e-mail]" <[e-mail]>,
    "[e-mail]" <[e-mail]>
From: Mark Andrews <[e-mail]>
References: <[e-mail]> <[e-mail]>
Subject: Re: Some thoughts/comments on draft-gont-6man-slaac-dns-config-issues-01
In-reply-to: Your message of "Thu, 16 Apr 2015 20:59:16 -0300."
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Date: Fri, 17 Apr 2015 10:33:48 +1000


On DNS server lifetimes there are several senarios to consider
depending upon which servers are being advertised.

1. Servers that are the embeded in the router or are proxied
	by the router.
2. Servers that are internal to the network but are not the
	router.
3. Servers that are external to the network and have a restricted
	client population (think ISP limited to its address
	ranges).
4. Servers that are external and don't have a restricted
	client population (think Google's public recursive
	servers).
5. a mixture of the above.

For 2 and 4 lifetime is totally independent of router lifetime.

For 1 and 3 the servers are only good as long as the router is up
and if you have a alternate exit route it would be better to not
use nameservers advertised by the router.  This is also a common
senario in homes.

That said I would just have the node update the servers based on a
merge of the available servers (if there are multiple routers) /
new set of servers and not remove them when the router goes down.

Mark
- -- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: [phone]                 INTERNET: [e-mail]

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