[SURBL-Discuss] Combined SURBL A record format (Was: Re: Bill
Stearns' sa-blacklistavailable as SURBL: ws.surbl.org)
jeffc at surbl.org
Wed Apr 21 02:42:08 CEST 2004
On Wednesday, April 21, 2004, 1:29:27 AM, Scott Truman wrote:
> I'm happy with either method obviously. Excuse my ignorance
> with regards to DNS lookups, but do all the A records come down
> with the first DNS lookup, or are they fetched each time from
> the remote
> What are the traffic overheads with incorporating either type
> of method - I would have thought that the bit mask method would
> cause less traffic - also with smaller zone transfers?
Multiple A records can result from a single query:
> % nslookup www.yahoo.com
> Name: www.yahoo.akadns.net
> Addresses: 22.214.171.124, 126.96.36.199, 188.8.131.52, 184.108.40.206
> 220.127.116.11, 18.104.22.168, 22.214.171.124, 126.96.36.199
> Aliases: www.yahoo.com
And they should all come from the locally cached copy of the zone
file, so they're fast.
A single bitmasked A record would be smaller but require a little
more application CPU to decode. Multiple A records may be faster
but they're bulkier. I find the multiple A records more readable.
It's one of those classic tradeoffs.
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