System Admin Q & A – XIII

Ques 1: – What Are Organizational Units in Active Directory ?

 Ans: – An organizational unit (OU) is a versatile container object used to organize objects within a domain into logical administrative groups. These logical administrative groups can include just one type of object or multiple types depending on how an administrator wants to structure it. Think of an OU like a large box that can contain many things, including other boxes (other OUs called sub-OUs), and those boxes can then contain additional boxes (additional sub-OUs) as well.

Ques 2: – What are Trees in Active Directory?

Ans: -A tree is a grouping or hierarchical arrangement of one or more Windows 2000 / 2003 domains that allows global resource sharing. A tree may consist of a single Windows 2000 domain or multiple domains in a contiguous namespace.
You can create a larger tree (contiguous namespace) by joining multiple domains in a hierarchical structure, since all domains within a single tree share a common namespace and a hierarchical naming structure. Following naming conventions, the domain name of a child domain is the name of that child domain appended with the name of the parent domain.

Ques 3: – What are the process states in Unix?

Ans: – As a process executes it changes state according to its circumstances. Unix processes have the following states

Running : The process is either running or it is ready to run .
Waiting : The process is waiting for an event or for a resource.
Stopped : The process has been stopped, usually by receiving a signal.
Zombie : The process is dead but have not been removed from the process table.

Ques 4: – What Are Forests in Active Directory ?

Ans: A forest is a grouping of one or more trees. As noted with our example of and, each of those is a tree within our forest even though their naming conventions are not related.

It does not matter if each Tree is made up with a single, or multiple domains. Forests allow organizations to group together divisions that do not use the same naming scheme, and may need to operate independently, but still need to communicate with the entire organization via transitive trusts, and share the same schema and configuration container. The first domain in the forest is called the forest root domain. The name of that domain refers to the forest, such as nwtraders.msft. By default, the information in Active Directory is shared only within the forest. This way, the forest is a security boundary for the information that is contained in the instance of Active Directory.

Ques 5: – What is the difference between Active and Passive FTP ?

Ans: – Active FTP : Client says to server port 21, that it want to start a FTP session. Server confirms from port 21 and initates a connection from a new dynamic port to the client. (note: client firewalls etc don’t know which port, so it is sometimes blocked as it is considered unwanted, and unrequested)

Passive FTP : Client says to server port 21, that they want to start a FTP session. Server confirms and tells the client to connect to specified dynamic port (8674 for instance) for FTP data transfer. Client connects to server port 8674, and server replies. (note: the server reply isn’t blocked because the firewall has logged that the client has at some point communicated with server on port 8674)

Ques 6: – 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 7: – Explain Zombie Process ?

Ans: – Zombie is a process state when the child dies before the parent process. In this case the structural information of the process is still in the process table.

Ques 8: – What is Curl and use of Curl ?

Ans: – Curl is a command line tool to transfer data from or to a server, using one of the supported protocols. The command is designed to work without user interaction. curl offers a busload of useful tricks like proxy support, user authentication, FTP upload, and much more.
We can use curl command to use :

  •  Troubleshoot http/ftp/cdn server problems.
  • Check or pass HTTP/HTTPS headers.
  • Upload / download files using ftp protocol or to cloud account.
  • Debug HTTP responses and find out exactly what an Apache/Nginx/Lighttpd/IIS server is sending to you without using any browser add-ons or 3rd party applications.

Ques 9: – What is netcat ?

Ans: – Netcat or nc is a simple Linux or Unix command which reads and writes data across network connections, using TCP or UDP protocol. We use this tool to open up a network pipe to test network connectivity, make backups, bind to sockets to handle incoming / outgoing requests and much more.

In this example, We tell nc to listen to a port # 4005 and execute /usr/bin/w command when client connects and send data back to the client:

#nc -l -p 4005 -e /usr/bin/w

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