Saturday, April 18, 2009

How to ?

how to run a server as a deamon

Friday, April 17, 2009

Qualys Inc - Final Round

How to add a user in a linux machine?

How to check for the dependencies of a package?

SSH connection for the first time - Trusted Host ?
How to do it without prompting for a password
How SSH will store the keys at server side? How to add user ?
SSH as a root without password ?

md5 length and which algorithm it uses? how do u do it linux / windows

regex ! every time !!!!
How to fetch a name called any name containing patel from a text file
what is ^ and what is $
$ENV variable
CPAN and Object Oriented Perl

/etc/password content ?

where rpm packages are installed

how to add remove and force the older version of rpm package

nmap and to give range and os fingerprinting option?

Version of each OS ?

Tuesday, April 14, 2009

Facebook Second Round - Telephonic

rc.conf ?

boot-screen messages ?

3 phase wire vs 1 phase ?

Monday, April 13, 2009

Qualys Inc - QA Intern interview questions

linux / windows

how to check if rpm package is installed or not?
How to install and uninstall module?
how to check the bootscreen text?

how software gets installed in linux, windows..etc
how to edit the registry entry in windows using gui


Socket programming apis
TCP Connection establishment and close
Socket APIs

traceroute ? how it works and whatis the meaning of stars ???

path MTU ...what is the purpose ?

TCP header format , flags, every thing

Port numbers again and again

Sliding window algorithm n how to solve the problem if rx is dropping the packet (manually set the limit)

Security related

SQL injection - every single time.....

IP Governance
How to test Nessus


Sudo code of sniffer

Perl - regular expression
text substitution
fatching text and all that stuff...

Friday, April 3, 2009

Facebook - Pre screening round

1)How kill command works
2)Bootcode ?

Sunday, March 29, 2009

Twitter interview questions - Operation Engineer-Search

Twitter interview questions - Operation Engineer-Search

How to check the files been created within last hour

How to check the largest file in the directory

How to do recursive copy?

How to scp to multiple machine

What is a command for storing the output of tcpdump in ASCII format

Difference between du and df

ssh on different port

what is find ?

Perl : How to find the most repeated IP address from the Textfile

Friday, March 27, 2009

Difference between du and df

du - disk usage statistics
df - free disk space.

In some cases it is possible that there is a difference between the outcome of df and du.

In 99.9% of the cases this is caused by a lock on the file system. Meaning, if an application opens a file or files and an other application deletes these files while they are opened they will still be calculated by df.

The df command calculates this by looking at the inode table and the inode table has not yet released those files, meaning that, according to the inode table, the files are still using space on the disk.

Generally the solution is to stop/start the process that has a lock on those non existing files and the results returned by df and du will be the same again.