Interview prep

How to migrate VMware VM from one host to another

First, create new datastore. You have to figure in location,type,nfs version, name and configuration, host accessibility.

What automation tools have you used and for what?

I have experience with several automation tools such as Nessus (security scanning), Ansible(Configuration and deployments), Jenkins (Continuous integration for our web applications, and Solarwinds (For network monitoring)

Tell me about ITIL

ITIL is a set of best practices for delivering IT services to customers. The primary focus is to maximize value to the customers by aligning resources with business needs.

Tell me about Redhat Satellite

Redhat Satellite is a system management tool that allows us to install and maintain servers for large scale environments. I've used Satellite to patch, manage configurations, and provision servers.

What is Scalability?

Scalability is the ability of a server to withstand heavyloads.

How do you clone a virtual machine?

Using the Vspher web client... 1. Select Virtual Machines and right click on the VM to be cloned and choose clone option. 2. Enter a name and location for VM 3. Select the cluster or host for the clone 4. Choose format and datastore 5. Choose clone options and customize OS (If required) Finish and it should be completed.

Tell me about Vmware

Vmware allows us to create virtual machines via a hypervisor. This allows us to have multiple servers on physical system.

How would would you troubleshoot a kernel panic?

- The first step is identifying at which stage the boot process has the system panic. (This is generally grub prompt) - Try and boot from the old kernel - Check the grub configuration files to see if the new kernel has the intramfs file - If the initramfs file is missing add it manually using the dracut command. - If the dracut command fails you'll possibly have to free up space. - The dracut command will add the initramfs file to the new kernel just reboot system and then boot from new kernel.

What configuration file do I go into to add a nameserver?

/etc/resolv.conf

How do you configure a github project with Jenkins?

1. Download Git to server 2. Login to github and get the weburl of project 3. Login to Jenkins portal click on New item 4. Add project name fill in fields 5. Select Build Now option Jenkins Dashboard 6. Click on the workspace option to view code or files

How do you install Maven on Jenkins?

1. Download the Maven from the Apache website 2. Create a Maven folder and extract tar file to that folder. 3. Then add M2 variables in the your bash profile. vi .bash_profile + M2_HOME=/OPT/MAVEN M2= /OPT/MAVEN/BIN $M2:$M2_HOME TO END OF PATH 4. use mvn --version to check installation 5.add maven plugins manage jenkins> manage plugins> Maven Integration & Invoker 6. Now finish setting up maven path Global configuration > add maven > insert home name and location Done

How do you deploy a .war file on tomcat server?

1. Make sure you have deploy to container plug in installed. manage jenkins > manage plugins > available > type in deploy to in search bar > install plugin 2. Create a new job, give name. 3.Give description of .war file 4. Copy repository URL into form 5. Fill in goals and options form with description of what .war file does. 6. Select build to container 7. Select .war file location. If unsure of name insert "**/*" in form. 8. Choose tomcat version in container 9. add proper credentials 10. add tomcat url and apply changes. The default location is usually "webapps" for .war file.

How would you troubleshoot a user access issue?

1. Ping server or gateway

How do you create a new Jenkins Job?

1. Select new item 2. Enter Job Name 3. Enter Description 4. Source Code Management (plug in) 5. Choose Build (target system) so execute shell for linux or execute windows for windows. 6. Insert command and Save 7. Then, you can find the project in your build history. The blue ball means the job is successful, the red ball means it fails, and the orange ball means partial success.

How does Jenkins help?

1. The code is built and tested after developer commits code. If build is successful Jenkins will deploy to the test server and notify deployment team. If build fails then jenkins will notify the dev team. 2. The code is built immediately after any of the developer commits, which makes it easy to detect whose code caused build to fail. 3. Automated build and test process saves time and reduces defects.

How do you harden a server?

1. Turn off all unneeded services. 2. Update the server. 3. Disable root access via ssh 4. Enable Firewall 5. Check for open ports

What are the 4 DNS servers?

1.Recursive Resolver 2.Root server 3.Top Level Domain Server 4.Authoritative Name Server

How do you install Jenkins?

1st- Install latest version of Java * yum install java version* 2- Install Apache tomcat. (To install Jenkins we need to deploy to jenkins war file using tomcat) *wget "tomcat link" then extract to a new folder* 3. Provide a username and password for tomcat by adding to the tomcat-users.xml file. *vi "path/tomcat-users.xml" adjust required fields (identified by must be changed) 4. Start tomcat and open browser and confirm tomcat is running. *./bin/startup.sh* *Enter localhost:8080 in browser* 5. Download Jenkins war file, open browser, select manager app and insert password 6. You will be directed to tomcat application manager page select deploy and give jenkins war file path. 7. Jenkins will be listed under appliications select and install suggested plugins. 8. You'll need to unlock jenkins. To do that copy the location listed, insert in terminal and cat to get the one time password. 9. Paste the password in, follow prompt to install plug ins and create admin account and then the installation is complete.

How do you create a LVM partition?

1st. Create partitions to be used and initialize them as physical volumes 2nd. Create the Volume Group 3rd. Create a logical volume 4. Create file system on a logical volume ( To make a file system, use the mkfs command then the path location) Then mount the filesystem to a created mount point.

How to troubleshoot a virtual machine with performance issues?

1st. Run Top Command 2nd. Check disk space to ensure file systems are filling up 3. Checking memory free -h 4. Check the log files var/log/secure 5. Ping 6. Telnet

What is a Kernel Panic?

A Kernel Panic is safety precaution taken by the operating systems kernel upon detecting a fatal error.

What is a container image?

A container image is an unchangeable file that includes executable code so it can run an isolated process. The image is made up of libraries, tools, and other platform settings.

Tell me about Ansible Tower

Ansible Tower is a Gui interface for managing Ansible. Tower allows you to share the SSH credentials without exposing them, logs job and manages inventories.

What have you used Ansible for?

Ansible can be used for provisioning, configuration management, continuous delivery, application deployment and security compliance. I've used Ansible for configuration management and application deployment.

Tell me about Ansible

Ansible is an open source configuration management tool. It is used to manage and configure servers on a large scale.

What are the steps in continuous integration/deployment?

Commit, build, test, and deploy.

What are the tools involved in the integration pipeline?

Continous Integration Server: Jenkins, Bamboo, Cruise Control, Team City Source Control Tool: CVS,SVN, GIT Build Tool: Ant, Maven, Ivy Automation Testing Framework- Selenium, Appium, Testcomplete

Give me a time where you had to create detailed documentation?

Detailed documentation shows how to do something in steps.

Tell me about EJB?

EJB- Stands for Enterprise Java Beans, these are server side components that are designed to be executed within the J2EE application server. EJB's enable you to write the business logic of your application later deploy.

How do you patch?

Essentially patching is running yum update. We patch from dev to prod. We run a patch in each tier once a week. The project manager approves of specific time to patch, the security team approves the patches to be applied to servers, the app team shuts down and starts applications, the database team shuts down and starts database and then the OS team runs yum update and reboots server.

How do you tune an Apache server?

First you want to access the configuration file (etc/httpd/conf/httpd.conf). Next, you'll need to calculate a good value for maxclient directives. This is based off the memory your apache process used and available memory on the server. Then, you will want to change max clients and server limit and restart server. Also deleting unnecessary apache modules will help.

How does VMotion work?

First, the state of the VM is encapsulated by a set of files stored on shared storage. Second, the active memory and state of the VM is quickly transferred over a high speed network. Third, the networks used by the virtual machine are also virtualized by the underlying ESX server. This ensures that even after migration the virtual machines network identity and connections are preserved.

What is Hudson?

Hudson is the original product that became Jenkins.

Tell me about containerization?

In containerization, the container is runtime environment that includes files, libraries and variables for the program to be executed.Since containers dont require their own operating systems to execute applications, they consume fewer resources.

What is continuous integration?

In continuous integration, after a code is committed to the repository the software is built and tested immediately. If the test is passed, the build is tested for deployment. If deployment is a success, the code is pushed to production.

What do you do specifically in your day to day?

In my day to day I provide support for redhat servers, applications, and services. A large part of my job is troubleshooting server issues and managing ticket requests. Its my job to monitor the servers for security risk and possible downtimes. I also do many other tasks such as building servers and configuring servers, backing up files and system data, and common support like managing user accounts and repairing hardware and software failures, patching etc

Tell me about Jenkins

In the Jenkins pipeline, first the developer commits the code to a repository like GIT. Then Jenkins creates a build of the code, part of that process is testing the code. Then assuming everything passes the test, the code can be deployed to the production environment. This whole process can be automated.

Tell me about JBOSS?

Jboss is an application server thats used for running Java and other web based applications. I've managed Jboss web servers before.

What is Jenkins?

Jenkins is a continuous integration application that allows your team to build and test software projects continuously. Jenkins can generate test reports, schedule tests, deploy directly to production or test environments, allow for easy notification

How do kill a process gracefully?

Kill -3

Tell me about Business Logic

Logic that is related to information within the application.

Tell me about LVM

Logical Volume Management is used for allocating and managing disk space. This allows us to allocate, strip, mirror, and resize disk.

How to generate an address/ptr record for command line?

NSLOOKUP, DIG

Tell me about NFS

Network file system is used for sharing of files and folders between linux systems. NFS allows you mount local file systems over a network so that remote hosts can interact with them as if they were mounted locally.

What are the 5 life cycle phases of ITIL?

Service Strategy - This is focusing on understanding customer needs and requirements. Service Design- This is focusing on turning strategies for service into detailed service description. Service Transition- This is focusing on building, validating, and delivering new and changed services to customers. Service Operations- This focuses on the day to day management of services Continual Service Improvement- This is focusing on improvements to service.

Tell me about Solarwinds

Solarwinds is a network performance monitor that helps us identify and resolve network performance issues. Solarwinds speeds troubleshooting and reduces downtime.

What tool would you use to analyze logs?

Splunk organizes logs, cipher logs

How do DNS servers resolve a DNS query?

The DNS recursor (DNS resolver) is the server that receives the query from the DNS client. It then interacts with other DNS servers to find the correct IP.

Tell about DNS

The Domain Name System is what allows users to connect to web-pages with domain names instead of ip addresses. The DNS resolves domain names to ip addresses.

Walk me through the DNS process

The recursive queries the root name server. The root server responds with address to of the TLD server that stores the information for its domains. The resolver queries the TLD server, the TLD server responds with the ip address of the domains authoritative name server. The authoritative name server will respond with the ip address of the origin server. The resolver will the pass the origin server ip address back to the client.

Tell me about Apache Web Service tuning

This editing the apache configuration to improves speed and performance of apache web server.

Tell me about Kickstart

This file contains configuration information server installation. The system reads this information at boot time and carries out the installation process without further input.

What do you know about J2EE containers?

This is a platform for running J2EE applications. Application components never interact directly with other application components. They use protocols and methods of the container for interacting with each other and platform services. A J2EE container consists of a web application and a EJB (Enterprise Java Bean) container.

Tell me about Nessus

This is a security tool that scans our systems for vulnerabilities and sends us a report to remediate them. Nessus has scheduled security audits and simulates attacks to pinpoint vulnerabilities. Nessus also detects missing security updates and patches

Tell me about Samba

This is used for network resources sharing across operating platforms. Using Samba, files and printers can be shared across multiple OS platforms. Samba uses SMB (server message block protocol)

What is the purpose of cloning a VM?

To create test environments from production servers.

Important commands for linux performance issue

Top- shows system summary info and tasks currently being managed Sar- this is a performance monitoring tool. It shows CPU info, Disk I/O, Swap and Memory, and more Vmstat-reports process information, memory, and cpu info Iostat- used for monitoring system input/output device loading by observing the time the devices are active in relation to average transfer rates. Free- Shows total amount of free and used physical and swap memory in the system. This also shows kernel buffers.

Tell me about Apache Server Tuning?

Tuning an Apache server comes down to the configuration. When your Apache server starts serving many requests, all those processes quickly fill the available memory. When your server runs out of ram, it will start killing processes that are considered memory hogs. Usually it starts with MYSQL processes.

What is VMotion?

VMotion allows you to migrate a running VM with zero downtime or service interruption.

What are some important files for NFS configuration?

etc/exports- the main configuration file for NFS exported files and directories. /etc/fstab- this makes mount persistent upon reboot /etc/sysconfig/nfs- Controls which port rpc and other services are listening.

Important Troubleshooting Commands

ifconfig- used to check available interfaces, assign ip addresses to interface, and enable or disable an interface. ifup- enables a specific interface ifdown- disables interface Ping- this is used to test connectivity between two inodes. Ping uses ICMP to communicate. Traceroute- determines packets traveling path Netstat- Displays connection info, routing table etc Dig-Queries DNS related information like A record,CNAME, MX record NSLOOKUP- another tool to show dns related information Route- shows and manipulates the ip routing table *route add* *route del* Host- finds name to ip ARP- Address resolution protocol is used to view and add the contents of the kernels arp tables ethtool- used to view, setting spped and duplex of network interface IWCONFIG- used to configure wireless network interface Hostname- Used to identify a network,use this to see hostname of box System-Config-Network- Gives a GUI to configure ip address, gateway, dns etc

How to make a mount point active?

mount -a