Pass the LPI LPIC-2 Certified Linux Engineer 202-450 Questions and answers with CertsForce

The word missing from the excerpt of a named.conf file is “acl”. This is because the excerpt is defining an access control list (ACL) for the DNS server. The ACL is used to restrict access to the DNS server and is defined in the named.conf file. The syntax for defining an ACL is:

acl name { address_match_list; };

where name is the name of the ACL, and address_match_list is a list of IP addresses, networks, or keywords that match the clients that are allowed or denied access.References:

LPIC-2 Overview

LPIC-2 202-450

BIND 9 Administrator Reference Manual

To allow X connections to be forwarded from or through an SSH server, the configuration keyword that must be set to yes in the sshd configuration file is XllForwarding. This keyword enables X11 forwarding, which is a mechanism that allows graphical applications to be run on a remote host and displayed on a local host. The sshd configuration file is usually located at /etc/ssh/sshd_config, and the XllForwarding keyword can be set globally or per host. For example:

XllForwarding yes

This will enable X11 forwarding for all hosts. To enable X11 forwarding for a specific host, use the Match directive, followed by the Host keyword and the host name or pattern. For example:

Match Host example.com XllForwarding yes

This will enable X11 forwarding only for the host example.com.

References:

X11 Forwarding using SSH

sshd_config - OpenSSH SSH daemon configuration file

How To Configure X11 Forwarding Using SSH In Linux

 The objectClass attribute of an LDAP object defines which other attributes can be set for the object. The objectClass attribute is a multi-valued attribute that specifies one or more object classes that the object belongs to. Each object class has a schema that defines the mandatory and optional attributes that the object can have. The objectClass attribute is required for every LDAP object and determines the nature and characteristics of the object. References:

Understanding the LDAP Protocol, Data Hierarchy, and Entry Components

LDAP Object Classes

 The ldappasswd command is an OpenLDAP client tool that can be used to change the password for an LDAP entry. It can be used to change the password of the user who is binding to the LDAP server, or the password of another user if the bind user has sufficient privileges. The ldappasswd command requires the user to specify the LDAP server location, the bind DN and password, the old password, and the new password. The old and new passwords can be given on the command line, through prompts, or from files. The ldappasswd command can also use SASL authentication mechanisms instead of simple authentication. The ldappasswd command follows the general syntax of:

ldappasswd [options] [user]

where user is the DN of the entry whose password is to be changed. If omitted, the bind DN is used.

References:

LPIC-2 Exam 202 Objectives, Objective 207.3: LDAP Operations

How To Change Account Passwords on an OpenLDAP Server, DigitalOcean

ldappasswd: change the password of an LDAP entry, openldap-clients Manual Page

How To Change an OpenLDAP Password, Tyler’s Guides

 The BIND option that should be used to limit the IP addresses from which slave name servers may connect is allow-transfer. This option specifies a list of IP addresses or networks that are allowed to request zone transfers from the master name server. Zone transfers are the mechanism by which slave name servers obtain a copy of the zone data from the master name server. By limiting the IP addresses that can request zone transfers, the master name server can prevent unauthorized access to the zone data and reduce the network load123 References:

LPIC-2 Overview

LPIC-2 202-450

BIND 9 Administrator Reference Manual

 The command exportfs is used to configure which file systems a NFS server makes available to clients. The exportfs command maintains a table of exported file systems in the /etc/exports file, which specifies the directories to be shared and the options for each host or network. The exportfs command can also be used to add, remove, or refresh the exported file systems without restarting the NFS service123 References:

8.6. Configuring the NFS Server - Red Hat Customer Portal

How to configure NFS on Linux - Learn Linux Configuration

How to configure Network File System on Linux | Enable Sysadmin

 The command that displays an overview of the Postfix queue content to help identify remote sites that are causing excessive mail traffic is qshape. This command shows the number of messages in the active, deferred, and hold queues, grouped by the next-hop domain name. It also shows the age distribution of the messages in each queue, which can help to identify domains that are slow or unreachable. The output of qshape looks like this:

The first column shows the next-hop domain name, or TOTAL for the sum of all domains. The second column shows the total number of messages in the queue for that domain. The remaining columns show the number of messages in different age ranges, in minutes. For example, the T column shows the number of messages that are less than 5 minutes old, the 5 column shows the number of messages that are between 5 and 10 minutes old, and so on. The last column shows the number of messages that are older than 1280 minutes (about 21 hours).

The qshape command can be used with different options to specify the queue name, the domain name pattern, the bucket size, the bucket count, the sort order, and the output format. For more information, see the qshape man page1.

References: You can find more information about the qshape command and its usage in the following resources:

qshape - Postfix queue analysis tool

Postfix Queue Management

The AuthType directive is used to specify the method of authentication for a directory or a location on the Apache HTTPD server. The directive has four possible values: None, Basic, Digest, and Form. Each value corresponds to a different module that implements the authentication mechanism.

None: This value means that no authentication is required. This is the default value and it can be used to override any inherited authentication settings.

Basic: This value means that the basic authentication method is used. This method is implemented by the mod_auth_basic module. It requires the user to enter a username and a password, which are sent to the server in plain text. Therefore, this method is not very secure and should be used with encryption, such as SSL or TLS.

Digest: This value means that the digest authentication method is used. This method is implemented by the mod_auth_digest module. It requires the user to enter a username and a password, which are hashed by the client and the server using a nonce (a random number) and a realm (a name for the protected area). Therefore, this method is more secure than the basic method, as it prevents replay attacks and password sniffing.

Form: This value means that the form authentication method is used. This method is implemented by the mod_auth_form module. It requires the user to fill out a web form with their credentials, which are sent to the server using the POST method. Therefore, this method is more flexible and user-friendly than the other methods, as it allows the use of custom forms and cookies.

References:

AuthType Directive

Authentication and Authorization - Apache HTTP Server Version 2.4

How to Create and Use .htpasswd

The LDIF excerpt shows the distinguished name (dn) of Robert Smith as “cn=Robert Smith, ou=people, dc=example, dc=com”. The organizational unit (ou) attribute is used to represent an organizational unit in which an entry resides. In this case, Robert Smith is part of the “people” organizational unit.

References:

[OpenLDAP Software 2.6 Administrator’s Guide: The LDIF File Format]: The official documentation of OpenLDAP on the LDIF file format, which explains the syntax and structure of LDIF entries and attributes.

[LDAP Data Interchange Format (LDIF) - Version 1]: The RFC 2849 document that defines the LDAP Data Interchange Format (LDIF), which is a common format for exchanging LDAP data.

The two commands shown in the image are used to drop packets with source or destination addresses from fe80::/64 in the FORWARD chain. The first command drops packets with source addresses from fe80::/64, while the second command drops packets with destination addresses from fe80::/64. Both commands will complete without an error message or warning because the affected network is not already part of another rule. The other statements are incorrect for the following reasons:

B. The rules disable packet forwarding because network nodes always use addresses from fe80::/64 to identify routers in their routing tables. This is false because network nodes do not use link-local addresses to identify routers in their routing tables. Instead, they use global or unique local addresses that are advertised by routers through router advertisements or DHCPv6.

C. ip6tables returns an error for the second command because the affected network is already part of another rule. This is false because there is no indication that the affected network is already part of another rule. Even if it was, ip6tables would not return an error, but rather append the new rule to the existing ones, unless the -I option was used to insert the new rule at a specific position.

E. The rules suppress any automatic configuration through router advertisements or DHCPv6. This is false because the rules only affect the FORWARD chain, which is used to process packets that are routed through the router. The rules do not affect the INPUT or OUTPUT chains, which are used to process packets that are destined for or originated from the router. Therefore, the rules do not interfere with the router’s ability to send or receive router advertisements or DHCPv6 messages.

References: LPIC-2 202 exam objectives, LPIC-2 202-450 Exam Prep: Network Configuration, IPv6 Firewalling with ip6tables, IPv6 Addressing and Basic Connectivity