Вопросы для сисадминов

Этот список вопросов был составлен моим прежним начальником – афроадминистратором (в смысле, он был из Южной Африки).
Эти вопросы вполне приемлемы для новых системных администраторов в нашей компании. Хотя их уже давно не принимали, и даже не искали, если только не считать моего нового начальника, который заменил прежнего.
И для меня сейчас эти вопросы оказались полезны, а то я слова забываю, но вот отсюда их вполне вспомнил. Ну и ответы в целом вполне знаю.
Если кому интересно, смотрите все эти вопросы под катом:

Questionnaire
Linux
1. Describe the Linux boot process, with as much detail as possible, starting from when the system is powered on, and ending when you get a prompt.
2. What is the name and the UID of the administrator user?
3. What command will show the available disk space on the Unix/Linux system?
4. Why is DNS important on the Network?
5. What is SNMP and what is it used for?
6. What is SSH port forwarding? What is the difference between local and remote port forwarding?
7. Describe briefly the steps you need to take in order to create and install a valid certificate for the site https://foo.example.com.
8. Can you have several HTTPS virtual hosts sharing the same IP? Explain?
9. What is the difference between a wildcard certificate and a multi-domain certificate?
10. What is a tunnel and how you can bypass a http proxy or corporate firewall?
11. What kind of keys are in ~/.ssh/authorized_keys and what it is this file used for?
12. What does :(){ :|:& };: do on your system?
13. When trying to unmount a directory it says it’s busy, how to find out which PID holds the directory?
14. How many NTP servers would you configure in your local ntp.conf and why?
15. You have a linux desktop, you open a web browser and enter http://foo.example.com in the address bar followed by hitting the Enter/Return key. Describe briefly what happens in the background from the time you hit ‘Enter/Return’ key, to the time that the page is displayed in your browser?

Networking
1. What is localhost and why would ‘ping localhost’ fail?
2. What is the difference between TCP and UDP?
3. What is the command used to show all open ports and/or socket connections on a machine?
4. Is 300.168.0.123 a valid IPv4 address?
5. Which IP ranges/subnets are “private” or “non-routable” (RFC 1918)?
6. What is the subnet mask, network and broadcast address for 10.99.2.0/22
7. What is a VLAN?
8. When a client running a web browser connects to a web server, what is the source port and what is the destination port of the connection?
9. How do you stop a DDoS attack?
10. How can you see content of an ip packet?
11. What are the three main security services that IPSEC VPN provides?
12. What are the 3 protocols used by IPSEC?
13. In which IPSEC Phase is the keys used for data encryption derived.
14. In IPSEC, If ESP provides both encryption and authentication, why is AH required.
15. Explain two methods by which two IPSEC routers can authenticate with each other.

MySQL
1. How do you create a user?
2. How do you provide privileges to a user?
3. Why should you run “mysql_secure_installation” after installing MySQL?
4. Explain briefly the differences between InnoDB and MyISAM.
5. Describe briefly the steps you need to follow in order to create a simple master/slave cluster.
6. You notice that replication between master and slave has become inconsistent and you don’t know how long this has been the case. Describe briefly the steps you need to follow in restore master/slave replication.
7. How do you check which jobs are running?
8. Your slave instance of MySQL says that InnoDB engine is not available, what do you do to re-instate InnoDB on the slave server?

Virtualisation
1. What are the minimum CPU and memory requirement of an ESXi host when building a 64bit OS that will take full advantage of ESXi features ?
2. What are the 4 typical ways storage can be added to a vSphere?
3. Name 4 things that happen on the VMkernel networking layer?
4. Name 5 of the 10 bits of information required when installing ESXi?
5. Can you mount a VMWare vmdk under linux to access the contents?
6. How do you install a driver via the esxi command line
7. You have two identical servers running VMWware (one is running dev VMs and the other is running critical productions databases). The one with the critical stuff has a broken motherboard. How would you quickly get access to the datastore of the server with the broken motherboard.

General System Administration
1. A careless sysadmin executes the following command: chmod 444 /bin/chmod – what do you do to fix this?
2. I’ve lost my root password, what can I do?
3. I’ve rebooted a remote server but after 10 minutes I’m still not able to ssh into it, what can be wrong?
4. If you were stuck on a desert island with only 5 command-line utilities, which would you choose and why?
5. You come across a random computer and it appears to be a command console for the universe. What is the first thing you type?
6. Tell me about a creative way that you’ve used SSH?
7. You have deleted by error a running script, what could you do to restore it?
8. What will happen on 19 January 2038?
9. Write a bash script to swap the values of two numeric variables without the use of a third variable

Security
1. You have been tasked to design and deploy a new secure, scalable and robust HA 3-tier web application environment (web->app->db), please explain your infrastructure design and the associated security controls you would deploy for putting the solution live on the internet.


You can read this post at LiveJournal.
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