LPIC-2 Certified Linux Engineer 202-450 Syllabus Exam Questions Answers

 TSIG stands for Transaction SIGnature, which is a mechanism for authenticating DNS messages using a shared secret key and a cryptographic hash algorithm. TSIG can be used to secure DNS updates, zone transfers, and queries between DNS servers and clients. To configure a BIND server to use TSIG, the following parameters should be added to the named.conf file:

• A key statement that defines the name, algorithm, and secret of the TSIG key. The name can be any arbitrary string, the algorithm can be one of the supported algorithms such as hmac-md5, hmac-sha1, hmac-sha256, etc., and the secret can be a base64-encoded string that represents the shared secret key. For example:

key “server.example.com” { algorithm hmac-md5; secret “skrKc4DoTzi/takIlPi7JZA==”; };

• A server statement that specifies the IP address or hostname of the remote server that will use the TSIG key, and the name of the key that should be used for communication. For example:

server 192.168.1.10 { keys { “server.example.com”; }; };

• A zone statement that indicates the zone name, type, and file of the zone that will use TSIG, and the name of the key that should be used for updates or transfers. For example:

zone “example.com” { type master; file “example.com.zone”; allow-update { key “server.example.com”; }; allow-transfer { key “server.example.com”; }; };

Option E shows the correct configuration parameters that should be added if the server should use the algorithm hmac-md5 and the key skrKc4DoTzi/takIlPi7JZA==. The other options are incorrect because they either use the wrong syntax, the wrong algorithm, the wrong key name, or the wrong secret.

References:

• LPIC-2 exam 202 objectives, topic 208.2, “Securing a DNS server”
• BIND 9 Administrator Reference Manual, chapter 6, “Access Control Lists and TSIG”
• How to Configure DNS Server with TSIG on CentOS 8

The Samba service that handles the membership of a file server in an Active Directory domain is winbindd. Winbindd is a daemon that provides a number of services to the Name Service Switch (NSS) capability of the system, such as resolving user and group information from a Windows NT server and authentication. Winbindd can also be used to join a Samba file server to an Active Directory domain and authenticate domain users to access the file shares12 References:

• Chapter 4. Using Samba for Active Directory Integration Red Hat Enterprise Linux 7 - Red Hat Customer Portal
• Winbind: Use of Domain Accounts - SambaWiki

The /etc/sysct1.conf file is used to configure kernel parameters at runtime. The net.ipv4.ip_forward parameter controls whether IP packet forwarding is enabled for IPv4. Setting it to 1 enables packet forwarding, while setting it to 0 disables it. This setting is applied at boot time and persists across system restarts. The other options are either incorrect or temporary solutions that do not survive a reboot. References: LPIC-2 201 exam objectives, LPIC-2 201-450 Exam Prep: Network Configuration

DANE stands for DNS-based Authentication of Named Entities. It is a protocol that provides a way to verify the association of X 509 certificates to DNS host names. X 509 certificates are digital documents that contain the public key and identity information of an entity, such as a web server or an email server. They are used to establish secure connections and authenticate the identity of the entity. However, the traditional way of obtaining and validating X 509 certificates relies on a hierarchical system of trusted third parties, called certificate authorities (CAs), which can be vulnerable to attacks or compromise. DANE aims to enhance the security and trust of X 509 certificates by using DNSSEC, which is a set of extensions to DNS that provide cryptographic signatures and validation for DNS records. DANE allows the owner of a domain name to publish the X 509 certificate or its fingerprint in a DNS record, called a TLSA record, which can be verified by the DNSSEC chain of trust. This way, the client can check the authenticity of the certificate directly from the DNS, without relying on external CAs. DANE can also be used to specify which CAs are authorized to issue certificates for a domain name, or to indicate that no CA is needed at all. DANE can be applied to various protocols that use X 509 certificates, such as HTTPS, SMTP, IMAP, POP3, etc.

References:

• DANE - Wikipedia
• DNS-Based Authentication of Named Entities (DANE) - Internet Society
• DANE: Taking TLS Authentication to the Next Level Using DNSSEC