[SURBL-Discuss] Combined SURBL A record format (Was: Re: Bill
Stearns' sa-blacklistavailable as SURBL: ws.surbl.org)
Jeff Chan
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
> server?
> 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?
Hi Scott,
Multiple A records can result from a single query:
> % nslookup www.yahoo.com
> Name: www.yahoo.akadns.net
> Addresses: 216.109.117.207, 216.109.118.75, 216.109.118.66, 216.109.118.77
> 216.109.118.73, 216.109.117.205, 216.109.117.204, 216.109.118.70
> 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.
Jeff C.
More information about the Discuss
mailing list