Q: How would you make the following SQL statement run faster? SELECT * FROM TABLEA WHERE COL1=’A’ AND COL2=’B';
A: Make sure that COL1 and COL2 have indexes.
Find out which condition will return less values and use that as the first conditonal.
Q: What is Data Mining
A: Data Minig is the process of sifting through extremeley large amounts of Data to find trends or relevent information.
Q: Name the Seven layers in the OSI Model.
A: Appication, Presentation, Session, Transport, Network, Data Link, Phyiscal
Q: What is one way to view a unix network share on a Windows computer, within explorer
A: NFS, The Unix computer can be running a NFS Server Daemon.
Q: How would you find all the processes running on your computer.
A: Unix, is ps -ef or ps -aux depending on version.
Q: What is DHCP
A: DHCP is a way to dynamically assign IP address to computers. Dyanmic Host Configuration Protocol
Q: What is HTTP Tunneling
A: HTTP Tunneling is a security method that encryptes packets traveling throught the internet. Only the intended reciepent should be able to decrypt the packets. Can be used to Create Virtual Private Networks. (VPN)
Q: Scenario: You have 9 identical looking balls, however one ball is heavier than the others. You have two chances to use a balance. How do you find out which ball is the heaviest?
A: Split into groups of three, randomly choose two groups and use balance on them. If one group is heavier, then discard the other 6 balls. If the two groups are the same weight. The heavier ball must be in the group that was not on the scale. Now randomly choose two balls and test on balance. If they are the same weight, the heaviest ball is on one that was not tested. Else the heaviest ball is already known from the balance.
5 Comments on Unix sysadmin interview questions
I was asked on an interview
What are the 5 layers in ftp
what does netstat do give 3 examples
how do you see what activity is happening on your server
what file contains the domain name
what happens when you issue an init command
what editor do you use
what shell do you use
what is your favorite shell
the five layers of ftp are
physical layer
data link layer
network/internet layer
transport layer
application layer
netstat (network statistics) is a command-line tool that displays network connections (both incoming and outgoing), routing tables, and a number of network interface statistics. It is available on Unix, Unix-like, and Windows NT-based operating systems.
Examples
To display the statistics for only the TCP or UDP protocols, type one of the following commands:
netstat -s -p tcp
netstat -s -p udp
To display active TCP connections and the process IDs every 5 seconds, type the following command (works on Microsoft XP and 2003 only):
netstat -o 5
OS X version
netstat -w 5
To display active TCP connections and the process IDs using numerical form, type the following command (works on Microsoft XP and 2003 only):
netstat -n -o
Ways to see activity on the server
These are Solaris answers
sar
top (if it’s installed)
vmstat
iostat
netstat
ps
who
w
whodo
Solaris file that contains the domain name
/etc/defaultdomain