├── README.md └── test.md /README.md: -------------------------------------------------------------------------------- 1 | linux-sysadmin-interview-questions 2 | ================================== 3 | 4 | A list of some of the questions which I've had to know during linux syadmin / devops interviews. 5 | -------------------------------------------------------------------------------- /test.md: -------------------------------------------------------------------------------- 1 | 1. Using the OSI model, which layer has the responsibility of making sure that the packet gets where it is supposed to go? 2 | 3 | 2. What is the subnet mask, network address and broadcast address for the following address: 123.65.47.62/22? 4 | 5 | 3. What command is used to show all open ports and/or socket connections on a machine? 6 | 7 | 4. What is NAT? What is it used for? 8 | 9 | 5. Which IP ranges/subnets are "private" or "non-routable" (RFC 1918)? 10 | 11 | 6. What is a packet filter and how does it work? 12 | 13 | 7. What is a proxy and how does it work? 14 | 15 | 8. What is ARP and what is it used for? 16 | 17 | 9. What is the difference between TCP and UDP? 18 | 19 | 10. What command is used to show the route table for a machine? 20 | 21 | 11. Explain asynchronous routing? 22 | 23 | 12. What is the purpose of a default gateway? 24 | 25 | 13. A TCP connection on a network can be uniquely defined by 4 things. What are those things? 26 | 27 | 14. When a client running a web browser connects to a web server, what is the source port of the connection? 28 | 29 | 15. What is the destination port of the connection? 30 | 31 | 16. What is SMTP? 32 | 33 | 16. What is an SMTP relay? 34 | 35 | 16. Give the basic scenario of how a mail message is delivered via SMTP 36 | 37 | 17. What function does DNS play on a network? 38 | 39 | 17. What is an A record? 40 | 41 | 17. What is an NS record? 42 | 43 | 17. What is an MX record? 44 | 45 | 17. What is a PTR record? 46 | 47 | 17. What is a DNS forwarder? 48 | 49 | 17. What command is used to lookup DNS records? 50 | 51 | 17. What is meant by "Reverse Lookup"? 52 | 53 | 18. What is LDAP and what is it used for? 54 | 55 | 19. What is a DN in LDAP? 56 | 57 | 20. What is SSH? 58 | 59 | 21. What is SSL? 60 | 61 | 22. What is IDS? 62 | 63 | 23. What is IPS? 64 | 65 | 24. What is the difference between IDS and IPS? 66 | 67 | 25. What is meant by the term "DOS Attack"? 68 | 69 | 26. What is RAID? 70 | 71 | 27. What is swap and what is it used for? 72 | 73 | 28. What command will show the available disk space on the Unix/Linux system? 74 | 75 | 29. How do you determine the public and prive IP addresses, if applicable, of a Unix/Linux system from the command line? 76 | 77 | 30. What Unix/Linux command will alter a file's ownership? 78 | 79 | 31. What Unix/Linux command will alter a file's permissions? 80 | 81 | 32. What Unix/Linux command will show all processes running on a system? 82 | 83 | 33. What Unix/Linux command will show the details of a file(permissions, size, timestamp)? 84 | 85 | 34. What Unix/Linux command would you use to list all currently loaded kernel modules? 86 | 87 | 35. What command would you use to telnet to port 7777 on a machine with IP address 10.10.10.128? 88 | 89 | 36. What Unix/Linux command(s) will show a system's current resource allocations? 90 | 91 | 37. What is the Unix/Linux command to remove a directory and its contents? 92 | 93 | 38. What is the name and location of the system log on a Unix or Linux system? 94 | 95 | 39. What would you do to recover a lost the root password to a Unix/Linux system? 96 | 97 | 40. What is the difference between hardlink and symlink? 98 | 99 | 41. What happens when you remove the source to a symlink? 100 | 101 | 42. What are some of the security risks of symlinks? 102 | 103 | 43. Explain a hardlink 104 | 105 | 44. Where is a filename stored? 106 | 107 | 45. What happens when a hardlink is removed 108 | 109 | 46. how do you know when a file is removed 110 | 111 | 47. Write a locking function in bash 112 | 113 | 48. What is a pre-emptive kernel, what does that mean to you? 114 | 115 | 49. What is an atomic operation? 116 | 117 | 50. How does a switch get a mac address? 118 | 119 | 51. What type of packet to discover a router? 120 | 121 | 52. How does traceroute work? 122 | 123 | 53. A careless sysadmin executes the following command: ```chmod 444 chmod``` - what do you do to fix this? 124 | --------------------------------------------------------------------------------