Radu Hociung [radu(_at_)ohmi(_dot_)org] wrote:
[...]
This is the output of the "spfquery -ip 1.1.1.1 -sender=rr.com -load"
that will be included with libspf2 1.0.6, which I will release soon.
[...]
Out of the domains participating to this mail-list, here are some DNS
load statistics below. What are the legitimate scenarios that make it
necessary to publish such expensive SPF records? (The "queries min-max"
column indicates the fewest number of queries necessary to find the
first IP address, and the max is the number of queries needed to
evaluate all mechs - ie, to get to the -all).
Domain |Queries min-max| TXT | PTR | A | MX |
---------------------+---------------+-------+-------+-------+-------+
[...]
These are excellent surveys. Thank you!
For a domain that needs this much mail infrastructure, there are a few
easy ways to reduce the DNS load:
1. implement a real-time DNS lookup table that can be accessed with the
exists:%{ir}.mailhosts.rr.com for instance.
2. add a single "A" record that resolves to a long list of IPs.
3. Use includes and specify the mail servers by IP address, the way
hotmail is doing it.
There is a 4th option I'd like to add:
4. Use subsidiary domains (florida.rr.com, etc.) _directly_ in sender
addresses, so the main rr.com domain isn't responsible for _all_
sending MTAs.