System Admin Q & A – XVI

Ques 1: – What is RCRON and where to use RCRON ?

Ans: – rcron is a powerful tool that helps system administrators in setting up cron jobs redundancy and failover over groups of machines. RCRON ensure that a job installed on several machines will only run on the active one at any time. High Availability using RCRON ( One Node will be stamped as Active and Second Node will be stamped as Passive ) , Same cron configuration will be on both , only difference would be active/passive state in a file.

For automatic Switching of active/passive state , we will be using KEEPALIVED Daemon , which utilizes the keepalive signal for communication between 2 nodes. After a signal is sent, if no reply is received the link is assumed to be down.

Ques 2: – What is Content Negotiation ?

Ans: – Load Balancing Clusters operate by having all workload come through one or more load balancing front-ends, which then distribute it to a collection of back end servers. If a node in a load-balancing cluster becomes inoperative, the load balancing software detects the failure and redirects requests to other cluster nodes. Red Hat Cluster Suite provides load- balancing through LVS (Linux Virtual Server).

Ques 3: – What is Puppet ?

Ans: – Puppet is a configuration Tool which is use to automate administration tasks.Puppet Agent(Client) sends request to Puppet Master (Server) and Puppet Master Push Configuration on Agent.

Ques 4: – What is Facter in Puppet ?

Ans: – Sometime you need to write manifests on conditional experession based on agent specific data which is available through Facter. Facter provides information like Kernel version,Dist release, IP Address, CPU info and etc.You can defined your facter also.

Ques 5: – What is Storage Clusters ?

Ans: -Storage clusters provide a consistent file system image across servers in a cluster, allowing the servers to simultaneously read and write to a single shared file system. With a cluster-wide file system, a storage cluster eliminates the need for redundant copies of application data and simplifies backup and disaster recovery. Red Hat Cluster Suite provides storage clustering through Red Hat GFS(Global File System).

Ques 6: – How to enable proxy settings in RSYNC and APT (ubuntu) ?

Ans: – Proxy Settings in RSYNC

# export  RSYNC_PROXY="http://:”
#  export RSYNC_PROXY="http://proxy.nextstep4it.com:8080”

Proxy settings for APT : Edit /etc/apt/apt.conf

Acquire::http::Proxy “http://:“;

Ques 7: – What is Virtual Hosting in Apache ?

Ans: – The term Virtual Hosting refers to the practice of running more than one web site (such as site1.nextstep4it.com and site2.nextstep4it.com) on a single machine. In Apache there are two types of virtual hosting.

1: IP Based Virtual Hosting

2: Name-Based Virtual Host

Ques 8: – What is Glusterfs ?

Ans: – GlusterFS is an open source network / cluster filesystem and based on a stackable user space design. It is used to achieve high availability of storage(i.e real time replication of files) across two linux machines using GlusterFS. Although glusterfs found its application in different areas like cloud computing, streaming media services, and content delivery networks.

Ques 9: – What is mutt and how to send mails using mutt from linux console ?

Ans: – Mutt is a small but powerful text-based e-mail client for Unix like operating systems. With mutt command one can send and read emails. Mutt supports both maildir & mbox mail formats. Mutt is compatible with POP & IMAP protocols.

Syntax :

# mutt -s “Subject of the Mail”  recipient-address@domain.com <  /dev/null

Ques 10: – What is Storage Clusters ?

Ans: -Storage clusters provide a consistent file system image across servers in a cluster, allowing the servers to simultaneously read and write to a single shared file system. With a cluster-wide file system, a storage cluster eliminates the need for redundant copies of application data and simplifies backup and disaster recovery. Red Hat Cluster Suite provides storage clustering through Red Hat GFS(Global File System).

System Admin Q & A – XIV

Ques 1: – What is Puppet ?

Ans: – Puppet is a configuration Tool which is use to automate administration tasks.Puppet Agent(Client) sends request to Puppet Master (Server) and Puppet Master Push Configuration on Agent. Communtication between the master and agent is done by exchaning the certificates.

Ques 2: – What is the use of etckeeper-commit-post and etckeeper-commit-pre on Puppet Agent ?

Ans:- etckeeper-commit-post: In this configuration file you can define command and scripts which executes after pushing configuration on Agent

etckeeper-commit-pre: In this configurati-on file you can define command and scripts which executes before pushing configuration on Agent

Ques 3: – What does IntelliMirror do?

Ans: – It helps to reconcile desktop settings, applications, and stored files for users, particularly those who move between workstations or those who must periodically work offline.

Ques 4: – What’s the major difference between FAT and NTFS on a local machine?

Ans: – FAT and FAT32 provide no security over locally logged-on users. Only native NTFS provides extensive permission control on both remote and local files.

Ques 5: – What’s the difference between standalone and fault-tolerant DFS (Distributed File System) installations?

Ans:- The standalone server stores the Dfs directory tree structure or topology locally. Thus, if a shared folder is inaccessible or if the Dfs root server is down, users are left with no link to the shared resources. A fault-tolerant root node stores the Dfs topology in the Active Directory, which is replicated to other

Ques 6: – What is Server Load Balancing ?

Ans: – Server Load Balancing (SLB) provides network performance and content delivery by implementing a series of algorithms and priorities to respond to the specific requests made to the network. In simple terms, SLB distributes clients to a group of servers and ensures that clients are not sent to failed servers.

Ques 7: – What do you mean a File System?

Ans: – File System is a method to store and organize files and directories on disk. A file system can have different formats called file system types. These formats determine how the information is stored as files and directories.

Ques 8: – Which Environment is most suitable for fibre Channel SANS ?

Ans: – Typically, Fibre Channel SANs are most suitable for large data centers running business-critical data, as well as applications that require high-bandwidth performance such as medical imaging, streaming media, and large databases. Fibre Channel SAN solutions can easily scale to meet the most demanding performance and availability requirements.

Ques 9: – What is ‘inode’ ?

Ans: – All UNIX files have its description stored in a structure called ‘inode’. The inode contains info about the file-size, its location, time of last access, time of last modification, permission and so on. Directories are also represented as files and have an associated inode.

Ques 10: – What is Health Check in refer to load balancer ?

Ans: – The Health Check feature of the load balancer that allows you to set parameters to perform diagnostic observations on the performance of web servers and web server farms associated with each appliance. Health checking allows you to determine if a particular server or service is running or has failed. When a service fails health checks, the SLB(server load balancing) algorithm will stop sending clients to that server until the service passes health checks again.

Ques 11: – What is SAN?

Ans: -A storage area network (SAN) is defined as a set of interconnected devices (e.g. disks and tapes) and servers that are connected to a common communication and data transfer infrastructure such as a fibre channel. The common communication and data transfer mechanism for a given deployment is commonly known as the storage fabric. The purpose of the SAN is to allow multiple servers access to a pool of storage in which any server can potentially access any storage unit.