Resolved Plesk's DNSBL server recommendation seems to be unpingable, so non-existent

[jmar83]

Server operating system version

Plesk 18.x, most current updates

Plesk version and microupdate number

Debian 10.x, most current updates

Hello

Cite from

https://xxx:8443/cp/server/mail/settings

: <Trennen Sie mehrere Einträge durch Semikola (Strichpunkte), zum Beispiel: 'zen.spamhaus.org;dnsbl.example.net'>

So i saw, the host zen.spamhaus.org ist NOT pingable (the other sone, dnsbl.example.com ist just an example, that ok)

Why?

(Same with DNSBL server from "nixspam", and also with most other DNSBL servers i found in the internet... that's really really strange i.m.o..!?)

 

[jmar83]

Hmm.. and also a bug here in forum so it seems, ;-) - no returns before posting and also not when i try to edit my post:

 

[jmar83]

Does nobody knows what that is?

 

[Peter Debik]

Why should the host be pingable? Maybe they try to reduce traffic or block some attacks so that the service was not enabled? Why not ask Spamhaus about it why they disabled ping on their servers?

 

[jmar83]

Thank you for your feedback.

My question was also because zen.spamhause.org ist a recommendation in plesk mail server config - so i was thinking that host is not available anymore so it maybe should be removed from plesk as a recommendation...

but i still don't understand how plesk mail server can reach that host via hostname if there is not domain name resolution - doesnt make sense i.m.o...

 

[Kaspar]

Ping is not a reliable method to check whether or not a remote service is available. If you want to know if zen.spamhause.org is working, make a DNS query to it in a way it is intended to work. For example running: dig +short 2.0.0.127.zen.spamhaus.org from your server.

 

[Peter Debik]

but i still don't understand how plesk mail server can reach that host via hostname if there is not domain name resolution - doesnt make sense i.m.o...

The name resolves, but the host does not offer the "ping" service. Ping can easily be disabled in a kernel setting, or icmp request can be blocked like iptables -A INPUT -p icmp --icmp-type echo-request -j DROP in iptables. Think of ping like a type of Internet request (just like www, but its not webservice, its ping service ...)

 

[jmar83]

Thank you very much!!