1z0-106 Exam Dumps : Oracle Linux 8 Advanced System Administration

Option A (Correct):The rule is applied to both IPv4 and IPv6 packets. Theinettable is used for filtering both IPv4 and IPv6 traffic, and since the rule is added to theinettable, it affects both IP versions.

Option E (Correct):The rule drops TCP packets inbound on port 80. The rule specifies theinputchain in thefiltertable, and it drops (drop) all TCP traffic (tcp) destined for port 80 (dport 80), which means any incoming TCP traffic on port 80 will be dropped.

Option B (Incorrect):The command does not automatically update the configuration on disk; the rule is applied immediately in memory but does not persist across reboots unless explicitly saved.

Option C (Incorrect):The rule specifies TCP packets only, not all traffic. Therefore, it does not drop traffic for protocols other than TCP.

Option D (Incorrect):Although this statement is correct, it is less specific than Option A, which is more accurate because it mentions both IP versions.

Option F (Incorrect):The rule applies to inbound traffic, not outbound, so it does not drop outbound traffic.

Oracle Linux Reference:Refer to:

Oracle® Linux 8: Managing Firewall Rules with nftables

Option A (Correct):The/procfile system is a pseudo-file system that contains runtime system information (e.g., system memory, mounted devices, hardware configuration, etc.). Files such as/proc/meminfoand/proc/cpuinfoprovide detailed information about memory and CPUs, respectively.

Option C (Correct):The/sysfile system, also known as sysfs, provides a view of the kernel's device model. It contains information about system hardware, including CPUs and memory. For example,/sys/devices/system/cpu/contains directories and files that provide detailed information about each CPU.

Option B (Incorrect):The/sysfile system does not contain a list of running processes. Running processes are listed in the/procfile system, with each process having its own directory under/proc.

Option D (Incorrect):/procdoes not contain a list of network drivers specifically. Network driver information is available under/proc/net, but this does not equate to a list of drivers.

Option E (Incorrect):The/sysfile system does not contain a list of mounted devices. Mounted devices are listed in/proc/mountsor the/etc/mtabfile.

Oracle Linux Reference:For more details, see:

Oracle® Linux 8: The/procand/sysFile Systems.

Option B: journalctl -p err shows only error log level.

Explanation:

The -p or --priority option in journalctl filters messages by their priority level.

When specifying asingle priority level, journalctl shows messagesonlyat that level.

The priority levels, as per syslog standards, are:

0: emerg

1: alert

2: crit

3: err

4: warning

5: notice

6: info

7: debug

Therefore, journalctl -p err displays messages with priorityerr (3)only.

Oracle Linux Reference:

Oracle® Linux 8: Managing Log Files- Section onFiltering Output withjournalctl:

"Use the -p option to display messages from the journal that have a specific priority level."

Example:

# journalctl -p err

Option D: journalctl -k shows kernel logs since the last boot.

Explanation:

The -k or --dmesg option filters messages from the kernel, equivalent to the output of the dmesg command.

This option implies -b, which limits the output to messages from the current boot.

Therefore, journalctl -k displays kernel messages since the last boot.

Oracle Linux Reference:

Oracle® Linux 8: Managing Log Files- Section onViewing Kernel Messages:

"Use the journalctl -k command to display kernel messages since the last system boot."

Example:

# journalctl -k

Option E: journalctl -p 6 shows all info log level messages and above.

Explanation:

When specifying a single numeric priority, journalctl displays messages withthat priority level and higher priority levels(i.e., lower severity).

Priority levels are ordered from 0 (highest severity) to 7 (lowest severity).

Therefore, journalctl -p 6 shows messages with priorities:

0 (emerg)

1 (alert)

2 (crit)

3 (err)

4 (warning)

5 (notice)

6 (info)

This includesinfo level messages (6)and all higher priority messages.

Oracle Linux Reference:

Oracle® Linux 8: Managing Log Files- Section onFiltering Output with journalctl:

"When you specify a single priority level, journalctl shows messages at that level and higher severity."

Example:

# journalctl -p 6

Why Other Options Are Not Correct:

Option A:journalctl -bl -p err fails if journal persistence is not configured.

Explanation:

The -b option displays messages from the current boot. This works even if journal persistence isnotconfigured because the logs from the current boot are stored in volatile memory (/run/log/journal).

Therefore, the command doesnot failif journal persistence is not configured.

Oracle Linux Reference:

Oracle® Linux 8: Managing Log Files- Section onJournal Volatility:

"By default, the journal stores logs in volatile memory and does not persist logs across reboots unless persistent storage is configured."

Option C:journalctl -p notice..warning shows all messages from notice to warning log level since the last boot.

Explanation:

The -p option allows specifying arangeof priorities. However, the correct order for the range should be from thehigher priority (lower number)to thelower priority (higher number).

Also, the priorities should be specified in the correct sequence, and ranges are inclusive.

Moreover, journalctl by default shows messages from all boots unless limited by the -b option.

Therefore, without -b, it does not limit messages to "since the last boot," making the statement incorrect.

Correct Command:

To display messages fromwarning (4)tonotice (5), the command should be:

# journalctl -p warning..notice -b

But even then, the priorities need to be specified correctly, and the command in Option C is incorrect.

Conclusion:

OptionsB,D, andEare correct because they accurately describe the behavior of the journalctl command in filtering and displaying log messages based on priority levels and sources.