benjojo.co.uk

one honk maybe more

uvok@furry.engineer posted 06 Jun 2024 05:29 +0000

Does anyone know where bgp.tools gets their forward / reverse DNS data from, i.e. which hostnames they forward and which IPs they reverse resolve? And how often is the data updated? Can I as an IP prefix owner trigger the update?

#bgptools #bgp

mark22k@layer8.space replied 06 Jun 2024 06:54 +0000
in reply to: https://furry.engineer/users/uvok/statuses/112568027570439767

@uvok Maybe a question for @benjojo .

benjojo replied 06 Jun 2024 10:18 +0000
in reply to: https://furry.engineer/users/uvok/statuses/112568027570439767

@uvok RDNS "SLA"'s are on https://bgp.tools/features

Forward DNS is done every ~14 days or so.

Both data sources are resolved "in rack" on AS206924. There used to be a button to force a RDNS update, but it's a little messy and I'd just direct people to wait a few days for it to update instead.

v4 RDNS updates work by checking everyones DNS SOA's regularly, and if they have changed then it rescans, assuming it has not already done so for since last week.

uvok@furry.engineer replied 06 Jun 2024 11:01 +0000
in reply to: https://benjojo.co.uk/u/benjojo/h/z9w78zdg49n54P3mNV

@benjojo thanks. I still don't understand how you know "which addresses" to resolve, e.g. when I look at a specific prefix and look at the Reverse DNS. (Where do the entries come from?).

I don't think you send PTR DNS requests for 2⁴⁸ addresses in case of a /48 IPv6 prefix. AXFR for the reverse zone is disabled in my case, so that can't be it neither.

Is it a ping scan of the prefix and the responding hosts are resolved?

benjojo replied 06 Jun 2024 11:16 +0000
in reply to: https://furry.engineer/users/uvok/statuses/112569333492479951

@uvok The "nailing down of" RFC8020 behaviour means I can quickly drill down into a zone to figure out where the PTRs are without doing 2^80 queries, almost all (except dynamic PTR generation stuff) follows the behaviour that allows this.