Which on these security warnings are serious?

Hello,
I'm using CentOS 8. I checked my server with Lynis and it showed me below information:
Code: -[ Lynis 3.0.0 Results ]-

Warnings (3):
----------------------------
! Couldn't find 2 responsive nameservers [NETW-2705]
https://cisofy.com/lynis/controls/NETW-2705/

! Found promiscuous interface [NETW-3015]
- Details : ens192
- Solution : Determine if this mode is required or whitelist interface in profile
https://cisofy.com/lynis/controls/NETW-3015/

! iptables module(s) loaded, but no rules active [FIRE-4512]
https://cisofy.com/lynis/controls/FIRE-4512/

Suggestions (42):
----------------------------
* If not required, consider explicit disabling of core dump in /etc/security/limits.conf file [KRNL-5820]
https://cisofy.com/lynis/controls/KRNL-5820/

* Check PAM configuration, add rounds if applicable and expire passwords to encrypt with new values [AUTH-9229]
https://cisofy.com/lynis/controls/AUTH-9229/

* Configure minimum encryption algorithm rounds in /etc/login.defs [AUTH-9230]
https://cisofy.com/lynis/controls/AUTH-9230/

* Configure maximum encryption algorithm rounds in /etc/login.defs [AUTH-9230]
https://cisofy.com/lynis/controls/AUTH-9230/

* When possible set expire dates for all password protected accounts [AUTH-9282]
https://cisofy.com/lynis/controls/AUTH-9282/

* Configure minimum password age in /etc/login.defs [AUTH-9286]
https://cisofy.com/lynis/controls/AUTH-9286/

* Configure maximum password age in /etc/login.defs [AUTH-9286]
https://cisofy.com/lynis/controls/AUTH-9286/

* Default umask in /etc/profile or /etc/profile.d/custom.sh could be more strict (e.g. 027) [AUTH-9328]
https://cisofy.com/lynis/controls/AUTH-9328/

* To decrease the impact of a full /tmp file system, place /tmp on a separate partition [FILE-6310]
https://cisofy.com/lynis/controls/FILE-6310/

* To decrease the impact of a full /var file system, place /var on a separate partition [FILE-6310]
https://cisofy.com/lynis/controls/FILE-6310/

* Consider disabling unused kernel modules [FILE-6430]
- Details : /etc/modprobe.d/blacklist.conf
- Solution : Add 'install MODULENAME /bin/true' (without quotes)
https://cisofy.com/lynis/controls/FILE-6430/

* Disable drivers like USB storage when not used, to prevent unauthorized storage or data theft [USB-1000]
https://cisofy.com/lynis/controls/USB-1000/

* Disable drivers like firewire storage when not used, to prevent unauthorized storage or data theft [STRG-1846]
https://cisofy.com/lynis/controls/STRG-1846/

* Split resolving between localhost and the hostname of the system [NAME-4406]
https://cisofy.com/lynis/controls/NAME-4406/

* Check your resolv.conf file and fill in a backup nameserver if possible [NETW-2705]
https://cisofy.com/lynis/controls/NETW-2705/

* Determine if protocol 'dccp' is really needed on this system [NETW-3200]
https://cisofy.com/lynis/controls/NETW-3200/

* Determine if protocol 'sctp' is really needed on this system [NETW-3200]
https://cisofy.com/lynis/controls/NETW-3200/

* Determine if protocol 'rds' is really needed on this system [NETW-3200]
https://cisofy.com/lynis/controls/NETW-3200/

* Determine if protocol 'tipc' is really needed on this system [NETW-3200]
https://cisofy.com/lynis/controls/NETW-3200/

* Install Apache mod_evasive to guard webserver against DoS/brute force attempts [HTTP-6640]
https://cisofy.com/lynis/controls/HTTP-6640/

* Consider hardening SSH configuration [SSH-7408]
- Details : AllowTcpForwarding (set YES to NO)
https://cisofy.com/lynis/controls/SSH-7408/

* Consider hardening SSH configuration [SSH-7408]
- Details : ClientAliveCountMax (set 3 to 2)
https://cisofy.com/lynis/controls/SSH-7408/

* Consider hardening SSH configuration [SSH-7408]
- Details : Compression (set YES to NO)
https://cisofy.com/lynis/controls/SSH-7408/

* Consider hardening SSH configuration [SSH-7408]
- Details : LogLevel (set INFO to VERBOSE)
https://cisofy.com/lynis/controls/SSH-7408/

* Consider hardening SSH configuration [SSH-7408]
- Details : MaxSessions (set 5 to 2)
https://cisofy.com/lynis/controls/SSH-7408/

* Consider hardening SSH configuration [SSH-7408]
- Details : Port (set 22 to )
https://cisofy.com/lynis/controls/SSH-7408/

* Consider hardening SSH configuration [SSH-7408]
- Details : TCPKeepAlive (set YES to NO)
https://cisofy.com/lynis/controls/SSH-7408/

* Consider hardening SSH configuration [SSH-7408]
- Details : X11Forwarding (set YES to NO)
https://cisofy.com/lynis/controls/SSH-7408/

* Consider hardening SSH configuration [SSH-7408]
- Details : AllowAgentForwarding (set YES to NO)
https://cisofy.com/lynis/controls/SSH-7408/

* Enable logging to an external logging host for archiving purposes and additional protection [LOGG-2154]
https://cisofy.com/lynis/controls/LOGG-2154/

* Check what deleted files are still in use and why. [LOGG-2190]
https://cisofy.com/lynis/controls/LOGG-2190/

* Add a legal banner to /etc/issue, to warn unauthorized users [BANN-7126]
https://cisofy.com/lynis/controls/BANN-7126/

* Add legal banner to /etc/issue.net, to warn unauthorized users [BANN-7130]
https://cisofy.com/lynis/controls/BANN-7130/

* Enable sysstat to collect accounting (no results) [ACCT-9626]
https://cisofy.com/lynis/controls/ACCT-9626/

* Audit daemon is enabled with an empty ruleset. Disable the daemon or define rules [ACCT-9630]
https://cisofy.com/lynis/controls/ACCT-9630/

* Utilize software pseudo random number generators [CRYP-8005]
https://cisofy.com/lynis/controls/CRYP-8005/

* Determine if automation tools are present for system management [TOOL-5002]
https://cisofy.com/lynis/controls/TOOL-5002/

* Consider restricting file permissions [FILE-7524]
- Details : See screen output or log file
- Solution : Use chmod to change file permissions
https://cisofy.com/lynis/controls/FILE-7524/

* Double check the permissions of home directories as some might be not strict enough. [HOME-9304]
https://cisofy.com/lynis/controls/HOME-9304/

* One or more sysctl values differ from the scan profile and could be tweaked [KRNL-6000]
- Solution : Change sysctl value or disable test (skip-test=KRNL-6000:<sysctl-key>)
https://cisofy.com/lynis/controls/KRNL-6000/

* Harden compilers like restricting access to root user only [HRDN-7222]
https://cisofy.com/lynis/controls/HRDN-7222/

* Harden the system by installing at least one malware scanner, to perform periodic file system scans [HRDN-7230]
- Solution : Install a tool like rkhunter, chkrootkit, OSSEC
https://cisofy.com/lynis/controls/HRDN-7230/

Follow-up:
----------------------------
- Show details of a test (lynis show details TEST-ID)
- Check the logfile for all details (less /var/log/lynis.log)
- Read security controls texts (https://cisofy.com)
- Use --upload to upload data to central system (Lynis Enterprise users)Which of these warnings are serious for a web server?

Thank you.