A Linux administrator is configuring a new internal web server fleet. The web servers are up and running but can only be reached by users directly via IP address. The administrator is attempting to fix this inconvenience by requesting appropriate records from the DNS team. The details are:
Hostname: devel.comptia.org
IP address: 5.5.5.1, 5.5.5.2, 5.5.5.3, 5.5.5.4
Name server: 5.5.5.254
Additional names: dev.comptia.org, development.comptia.org
Which of the following types of DNS records should the Linux administrator request from the DNS team? (Select three).
Correct Answer:
BDE
The Linux administrator should request the following types of DNS records from the DNS team:
✑ A: This record type is used to map a hostname to an IPv4 address. The administrator needs four A records for devel.comptia.org, one for each IP address (5.5.5.1, 5.5.5.2, 5.5.5.3, 5.5.5.4). This will allow users to access the web servers by using the hostname devel.comptia.org instead of the IP addresses1.
✑ CNAME: This record type is used to create an alias for another hostname. The administrator needs two CNAME records, one for dev.comptia.org and one for development.comptia.org, both pointing to devel.comptia.org. This will allow users to access the web servers by using any of these three hostnames interchangeably1.
✑ NS: This record type is used to delegate a domain or a subdomain to another name server. The administrator needs one NS record for comptia.org, pointing to 5.5.5.254, which is the name server that hosts the records for the subdomain devel.comptia.org2. This will allow users to resolve the hostnames under comptia.org by querying the name server 5.5.5.2542.
The other record types are not relevant for the administrator’s task:
✑ MX: This record type is used to specify the mail exchange server for a domain or a subdomain1. The administrator does not need this record type because the web servers are not intended to handle email traffic.
✑ PTR: This record type is used to map an IP address to a hostname, which is the reverse of an A record1. The administrator does not need this record type because the web servers are not expected to be accessed by their IP addresses.
✑ RRSIG: This record type is used to provide digital signatures for DNSSEC, which is a security extension for DNS that verifies the authenticity and integrity of DNS responses3. The administrator does not need this record type because it is not mentioned in the task requirements.
✑ SOA: This record type is used to provide information about the authoritative name server and other parameters for a domain or a subdomain1. The administrator does not need this record type because it is usually created automatically by the name server software when a new zone file is created4.
✑ TXT: This record type is used to store arbitrary text data that can be used for various purposes, such as SPF, DKIM, DMARC, etc1. The administrator does not need this record type because it is not related to the web server functionality.
✑ SRV: This record type is used to specify the location and port number of a service that runs on a domain or a subdomain1. The administrator does not need this record type because the web servers use the standard HTTP port 80, which does not require an SRV record.
References: 1: DNS Record Types – CompTIA Network+ N10-007 – 1.8 2: NS Record - DNSimple Help 3: DNSSEC - Wikipedia 4: SOA Record - DNSimple Help
Which of the following is the best tool for dynamic tuning of kernel parameters?
Correct Answer:
A
The tuned application is the best tool for dynamic tuning of kernel parameters, as it monitors the system and optimizes the performance under different workloads. It provides a number of predefined profiles for typical use cases, such as power saving, low latency, high throughput, virtual machine performance, and so on. It also allows users to create, modify, and delete profiles, and to switch between them on the fly. The tuned application uses the sysctl command and the configuration files in the /etc/sysctl.d/ directory to adjust the kernel parameters at runtime.
References
✑ Chapter 2. Getting started with TuneD - Red Hat Customer Portal, paragraph 1
✑ Kernel tuning with sysctl - Linux.com, paragraph 1
Which of the following will prevent non-root SSH access to a Linux server?
Correct Answer:
A
This file prevents any non-root user from logging in to the system, regardless of the authentication method. The contents of the file are displayed to the user before the login is terminated. This can be useful for system maintenance or security reasons12.
References: 1: Creating the /etc/nologin File - Oracle 2: How to Restrict Log In Capabilities of Users on Ubuntu
A systems administrator is deploying three identical, cloud-based servers. The administrator is using the following code to complete the task:
Which of the following technologies is the administrator using?
Correct Answer:
D
The code snippet is written in Terraform language, which is a tool for building, changing, and versioning infrastructure as code. Terraform uses a declarative syntax to describe the desired state of the infrastructure and applies the changes accordingly. The code defines a resource of type aws_instance, which creates an AWS EC2 instance, and sets the attributes such as the AMI ID, instance type, security group IDs, and key name. The code also uses a count parameter to create three identical instances and assigns them different names using the count.index variable. This is the correct technology that the administrator is using. The other options are incorrect because they use different languages and syntaxes for infrastructure as code. References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 19: Managing Cloud and Virtualization Technologies, page 559.
A Linux administrator needs to create a symlink for /usr/local/bin/app-a, which was installed in /usr/local/share/app-a. Which of the following commands should the administrator use?
Correct Answer:
A
To create a symlink for /usr/local/bin/app-a, which was installed in /usr/local/share/app-a, the administrator can use the command ln -s /usr/local/share/app-a /usr/local/bin/app-a (A). This will create a symbolic link named /usr/local/bin/app-a that points to the original file /usr/local/share/app-a. The other commands will not create a symlink, but either move, copy, or synchronize the file. References:
✑ [CompTIA Linux+ Study Guide], Chapter 3: Working with Files, Section: Creating Links
✑ [How to Create Symbolic Links in Linux]