I've noticed a server where freshclam was unable to resolve database.clamav.net address.
So I've fixed a little glitch that results in "unknown error" instead of "host not found" or "no ip address"

this off course does not solve the problem, but investigating, I've discovered some weird things not related to clamav

nslookup database.clamav.net

Server: dns.interbusiness.it
Address: 151.99.125.2

Non-authoritative answer:
Name: db.it.clamav.net
Addresses: 193.206.139.37, 213.92.8.5
Aliases: database.clamav.net, db.local.clamav.net


ping database.clamav.net
Host not found: database.clamav.net.

any clue? this may be one of sources of freshclam problems on some pc

the "no ip address" error is described as:

Valid name, no data record of requested type.
The requested name is valid and was found in the database, but it does not have the correct associated data being resolved for. The usual example for this is a host name-to-address translation attempt (using gethostbyname or WSAAsyncGetHostByName) which uses the DNS (Domain Name Server). An MX record is returned but no A record—indicating the host itself exists, but is not directly reachable.

I've made a little tool that checks if your dns works correctly, first try with default "database.clamav.net" then try something else like google or so
https://oss.netfarm.it/clamav/files/dnschecker.exe https://oss.netfarm.it/clamav/files/dnschecker.exe