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On 11/21/14 6:12 PM, Paul Hoffman wrote:
| Clearly, different people view the "advantages" and "disadvantages"
| separately. The wording below tries to make the comparisons neutral
| while still fully stating what the differences are. Note that I
| made this wording specific to BIND: when we have other multi-view
| servers  in the examples, I'll write specific wording for them. Is
| the following (re-)wording correct and complete?

I chose the wording I did in the version I sent very carefully,
because the issues discussed are exactly the same if you use two views
in the same instance, or if you use multiple instances. The latter
issue is particularly relevant at larger sites since I could easily
imagine a site setting up their own root instance with a slaved copy
of the zone that their resolvers are configured to forward to.

Bob's request was to outline the pros and cons of each method, so that
people who are less sophisticated about these things will know how to
make a decision about what method to choose. I think showing that two
views would operate the same as two different instances is important
for meeting that goal.

Regarding making the wording BIND specific, I'm not opposed to that
per se, I'm just curious if there is any other commonly used software
capable of doing both authority and recursion in the same instance. If
there is, we should not make the wording specific to BIND.

| ========== BIND handles both DNSSEC validation and caching of
| changed authoritative information differently depending on the
| whether the configuration is to use two separate views (one for the
| authoritative zone, one for recurison) or to use the same view for
| both servers.

The sentence above makes little sense, and could even be described as
misleading. If you want to leave the following two paragraphs the way
you have them, and account for what I discussed above, you could open
with something like this:

Name server software that permits authoritative zones and recursion to
exist in the same instance (such as BIND) will treat the zone data
differently if it is slaved into a separate view (or a separate
instance of the software) versus slaving the zone into the same view
or instance that is also performing the recursion.

| Validation: When using separate views, the DS records in the slaved
| zone will be validated as the zone is refreshed or updated.

That is factually incorrect. They will be validated as they are used.
I'm not sure where this obsession came from about validating the zone
when it's transferred. That's never been a part of DNSSEC.

Here's my previous paragraph on this, modified to fit your format a
bit better:

When using a separate view in a recursor that is also performing
DNSSEC the DS records in the slaved zone will be validated as they are
used. In BIND this validation does not occur when the zone is slaved
into the same view where the recursion is occurring.

| When using the same view, this validation does not occur for the
| slaved zone.
|
| Caching: When using separate views, the recursive server will cache
| all of the queries it looks up, just as it would using the
| traditional root hints method. Thus, as the zone in the other view
| is refreshed or updated, changed information will not appear in the
| recursive server until the TTL of the old record times out;
| currently the TTL for DS and delegation NS records is two days.
| When using the same view, as the zone is refreshed or updated, all
| zone data in the recursive server will be updated as soon as it
| receives its copy of the zone.

There are several grammatical problems with this paragraph. Here's an
update with some other refinements:

When using separate views the recursive server will cache all of the
queries for the slaved zone, just as it would using the traditional
root hints method. Thus, as the zone in the other view is refreshed or
updated changed information will not appear in the recursive server
until the TTL of the old record times out. Currently the TTL for DS
and delegation NS records in the root zone is two days. When using the
same view all zone data in the recursive server will be updated as
soon as it receives its copy of the zone.

hth,

Doug


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