linux interview questions & answers

7/25/2019 Linux Interview Questions & Answers

1/87

LINUX INTERVIEW QUESTIONS

1} what is inode?

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. irectories are

also represented as files and have an associated inode.

2} what are the process states in UNIX?

As a process e!ecutes it chan"es state accordin" to its circumstances.

Uni! processes have the follo#in" states$%unnin"$ The process is either runnin" or it is read& to run . 'aitin"$

The process is #aitin" for an event or for a resource. (topped$ The

process has been stopped, usuall& b& receivin" a si"nal. )ombie$ The

processes are dead but have not been removed from the process table.

3} what command should you use to check the number o

iles and disk space used and each users deined !uotas?

rep*uota

"} what command is used to remo#e the password assi$ned

to a $roup?

"pass#d +r

%} what can you type at a command line to determine which

shell you are usin$?

echo (//

&} write a command to ind all o the iles which ha#e been

accessed within the last 3' days(


2/87

find 0 -t&pe f -atime -12 3 filename.t!t

)} what is a *ombie?

)ombie is a process state #hen the child dies before the parent

process. In this case the structural information of the process is still in

the process table.

)} what daemon is responsible or trackin$ e#ents on your

system?

s&slo"d

+} what do you mean a ,ile -ystem?

4ile (&stem is a method to store and or"anize files and directories on

dis5. A file s&stem can have 6 different formats called file s&stem t&pes.

These formats determine ho# the information is stored as files and

directories.

78 tell me the name of director& structure hierarch& for /inu!

0root 0boot 0bin 0sbin 0proc 0mnt 0usr 0var 0lib 0etc 0dev 0opt 0srv

0tmp 0media

1'} what does .boot directory contains?

The 0boot0 director& contains static files re*uired to boot the s&stem,

such as the /inu! 5ernel, boot loader confi"uration files. These files

are essential for the s&stem to boot properl&.

11} i someone deletes .boot directory rom your ser#er/

than what will happen?

In that case &our server #ill be in unbootable state. 9our (erver cant

boot #ithout 0boot director& because this director& contains all

bootable files

12} what does .de# directory contain?


3/87

The 0dev director& contains all device files that are attached to s&stem

or virtual device files that are provided b& the 5ernel.

13} what is the role o ude# daemon?

The udev demon used to create and remove all these device nodes or

files in 0dev0 director&.

1"} what kind o iles or nodes .de#. directory contains and

how do I access or see de#ice iles?

:loc5 evice 4iles$-

:loc5 device files tal5s to devices bloc5 b& bloc5 ;< bloc5 at a time = ?


4/87

0dev0psau!

1&} tell me the name o de#ice ile or parallel port

0rinters(

0dev0lp2

1)} what does .etc.X11. directory contains?

The 0etc0X


5/87

of the Oournal used to maintain consistenc&. The default Oournal size

ta5es about a second to recover, dependin" on the speed of the

hard#are.

21} 4ny idea about et" ile system?

The e!tJ or fourth e!tended files&stem is a Oournalin" file s&stem

developed as the successor to e!t1. !tJ files&stem released as a

functionall& complete and stable files&stem in /inu! #ith 5ernel

version 6.K.6.

4eatures of e!tJ file s&stem$-


6/87

m5e6fs -t e!tJ 0dev0L

2%} 7plain .proc ilesystem?

0proc is a virtual files&stem that provides detailed information about

/inu! 5ernel, hard#ares and runnin" processes. 4iles under 0proc

director& named as Lirtual files. :ecause 0proc contains virtual files

thats #h& it is called virtual file s&stem. These virtual files have uni*ue

*ualities. Eost of them are listed as zero b&tes in size. Lirtual files

such as 0proc0interrupts, 0proc0meminfo, 0proc0mounts, and

0proc0partitions provide an up-to-the-moment "limpse of the s&stems

hard#are. Dthers, li5e the 0proc0files&stems file and the 0proc0s&s0

director& provide s&stem confi"uration information and interfaces.2&} 6an we chan$e iles parameters placed under .proc

directory?

9es To chan"e the value of a virtual file, use the echo command and a

"reater than s&mbol =3 to redirect the ne# value to the file. 4or

e!ample, to chan"e the hostname on the fl&, t&pe$

echo http$00###.ne!tstepJit.com3 0proc0s&s05ernel0hostname

2)} 8hat is the use o sysctl command?

The 0sbin0s&sctl command is used to vie#, set, and automate 5ernel

settin"s in the 0proc0s&s0 director&.

2+} .proc. directory contains a number o directories with

numerical names( 8hat is that?

These directories are called process directories, as the& are named

after a pro"rams process I and contain information specific to that

process.

29} 8hat is :4I;?

%AI, stands for %edundant Arra& of Ine!pensive is5s. %AI is a

method b& #hich same data or information is spread across several
http://www.nextstep4it.com/http://www.nextstep4it.com/


7/87

dis5s, usin" techni*ues such as dis5 stripin" =%AI /evel 2, dis5

mirrorin" =%AI /evel


8/87

%AI /evel < is based on Eirrorin" techni*ue. /evel < provides

redundanc& b& #ritin" identical data to each member dis5 of the arra&.

The stora"e capacit& of the level < arra& is e*ual to the capacit& of one

of the mirrored hard dis5s in a ard#are %AI or one of the mirroredpartitions in a (oft#are %AI. %AI < provides redundanc& means

"ood protection a"ainst dis5 failure. In %AI < #rite speed is slo# but

read speed is "ood.

3"} 7plain :4I; %?

%AI /evel ? is based on rotatin" parit& #ith stripin" techni*ue.

%AI-? stores parit& information but not redundant data =but parit&

information can be used to reconstruct data. The stora"e capacit& of(oft#are %AI level ? is e*ual to the capacit& of the member

partitions, minus the size of one of the partitions if the& are of e*ual

size. The performance of %AI ? is based on parit& calculation process

but #ith modern CUs that usuall& is not a ver& bi" problem. In %AI

? read and #rite speeds are "ood.

M

3%} 8hich kernel module is re!uired or -otware:4I;?RmdS module

3&} which utility or command is used or creatin$ sotware

:4I;sor :57


9/87

pieces of the stripe on each dis5 The pieces a stripe is bro5en into are

called chun5s.To "et "ood performance &ou must have a reasonable

chun5 size.

4or bi" I0Ds #e re*uired small chun5s and for small I0Ds #e re*uiredbi" chun5s.

39} 8hat is -840 -pace?

(#ap space in /inu! is used #hen the amount of ph&sical memor&

=%AE is full. If the s&stem needs more memor& resources and the

%AE is full, inactive pa"es in memor& are moved to the s#ap space.

'hile s#ap space can help machines #ith a small amount of %AE, it

should not be considered a replacement for more %AE. (#ap space islocated on hard drives, #hich have a slo#er access time than ph&sical

memor&.

"'} 8hat are the steps to create -840 iles or 0artition?+

Create s#ap partition or file + 'rite special si"nature usin" Rm5s#apS

+ Activate s#ap space b& Rs#apon +aS command + Add s#ap entr&

into 0etc0fstab file

"1} 5ow you will create swap ile o si*e " => and eplainswap ileentry in .etc.stab ile?

Use RddS command to create s#ap file.

dd if>0dev0zero of>0('A4I/ bs>J

m5s#ap 0('A4I/

s#apon +a

ntr& into 0etc0fstab file.0('A4I/ s#ap s#ap defaults 2 2

"2} ell me the steps to remo#e the swap ile?

4irstl& disable the s#ap file b& Rs#apoffS command. %emove (#ap file

entr& from 0etc0fstab file. No# remove the s#ap file b& RrmS


10/87

command.

"3} 8hat can we do with @partedA command or utility?+

Lie# the e!istin" partition table + Add partitions from free space or

additional hard drives + Chan"e the size of e!istin" partitionsJJ8 o# #e #ill chec5 free space on drive 0dev0sda #ith parted

command Fparted 0dev0sda

print

"%} 6an we resi*e the si*e o a partition?

9es, #e can resize the size of partition b& RpartedS command.

Fparted 0dev0sda

printTo resize the partition, use the resize command follo#ed b& the minor

number for the partition, the startin" place in me"ab&tes, and the end

place in me"ab&tes. 4or e!ample$

resize 1


11/87

Fv"create L/2 0dev0sda6 + Create lo"ical volume from volume

"roup b& RlvcreateS command.

Flvcreate -/


12/87

%"} 5ow you will check on Dour ser#er or system de#iceE

mapper is installed or not?

Chec5 the follo#in" file. Fcat 0proc0misc

if this file contains Rdevice-mapperS term it means device mapper is

installed on &our s&stem.

%%} 5ow are snapshots in


13/87

umount 0dev0Qv"name30Qlvname3

and then use the lvremove command$

lvremove 0dev0Qv"name30Qlvname3

&1} 8hich command is used to create


14/87

CU( stands for RCommon UNIX rintin" (&stemS. CU( is a open

source printin" s&stem developed b& Apple Inc. CU( uses the

Internet rintin" rotocol =I to allo# local printin" and print

sharin".&&} 8hat is the location o lo$ iles or 6U0-?

The lo" files for the CU( printin" s&stem are located in the

0var0lo"0cups0 director&.

&)} 8hat is DUC?

9UE stands for 9ello# do" Updater, Eodified because it is based on

9U, the 9ello# do" Updater. 'here does the name 9ello# do" comefrom 9ello# o" is a version of /inu! for the o#er Architecture

hard#are and is %E-based, Oust li5e %ed at nterprise /inu! and

4edora. 9U, and later 9UE, #ere #ritten b& the /inu! communit& as

a #a& to maintain an %E-based s&stem.

K8 'hat are the advanta"es of 9UE

+ Automatic resolution of soft#are dependencies. + Eultiple soft#are

locations at one time. + Abilit& to specif& particular soft#are versionsor architectures.

&9} 5ow you will install sotware by DUC?

&um install Qp5"name3

)'} 8hich option is re!uired to assume the answer @yesA to

any !uestions asked durin$ installation o packa$e

dependencies or DUC?

The R-&S option is used to assume the ans#er R&esS.

4or !ample

&um -& install s*uid

)1} 5ow to remo#e a sotware by DUC?


15/87

&um remove Qp5"name3

)2} 5ow Cany :un


16/87

Intel EKJT

iaKJ IntelZ Itanium

ppc 16-bit I:EZ D'%, I:E e(erver\ p(eriesZ, and I:E e(erver

i(eriess172! KJ-bit I:E e(erver (&stem z

)%} 5ow to install


17/87

it *ueries the %E database for #hich pac5a"e o#ns Qfilename3.

'hen specif&in" a file, specif& the absolute path of the file.

+2} 5ow to #eriy all installed packa$es?

rpm +La

+3} 5ow to #eriy the si$nature o an rpm?

rpm -@ test-0home 0home e!t1 acl < 6

No# remount 0home partition #ith acl option.

mount -t e!t1 -o acl 0dev0sda1 0home

++} 5ow to Biew 46


18/87

setfacl +remove-all Qfile-name3

9'} 8hat is the dierence between pop3 and imap

protocols?

D1 =ost Dffice rotocol is the most commonl& used internet

mail protocol.It#or5s on


19/87

F pass#d Qusername3 -l

This mi"ht be useful in the situation #here &ou dont #ant to

permanentl& remove the user, but &ou Oust #ant it disabled and no

lon"er able to use the s&stem. The user #ill still receive emails fore!ample, but he #ill not be able to lo"in and chec5 them out.

To re-enable the account ,Oust use belo# command


20/87

repeatedl& ,

at command is used to schedule the tas5 onl& once i.e to run onl& one

time.

9%} 8hat is network bondin$ in noneDN:DDT>&es

%eplace above I address #ith &our actual I address. (ave file and

e!it to shell prompt.

(tep F6$ Eodif& eth2 and eth< confi" files$


21/87

Dpen both confi"uration usin" vi te!t editor and ma5e sure file read as

follo#s for eth2 interface F vi 0etc0s&sconfi"0net#or5-scripts0ifcf"-

eth2 Eodif&0append directive as follo#s$ LIC>eth2

U(%CT/>no DN:DDT>&es EA(T%>bond2 (/AL>&es:DDT%DTD>none

Dpen eth< confi"uration file usin" vi te!t editor$

F vi 0etc0s&sconfi"0net#or5-scripts0ifcf"-etheth< U(%CT/>no DN:DDT>&es EA(T%>bond2

(/AL>&es :DDT%DTD>none

(ave file and e!it to shell prompt.

(tep F 1$ /oad bond driver0module

Ea5e sure bondin" module is loaded #hen the channel-bondin"

interface =bond2 is brou"ht up. 9ou need to modif& 5ernel modules

confi"uration file$

F vi 0etc0modprobe.conf Append follo#in" t#o lines$

alias bond2 bondin" options bond2 mode>balance-alb miimon>


22/87

ermanent ' addr$ 22$2c$67$cK$be$?7

(lave Interface$ ethlock in


25/87

(tatus

Information about other metadata structures

If this information lost, &ou are in trouble =data loss so /inu!

maintains multiple redundant copies of thesuperbloc5 in ever& files&stem. This is ver& important in man& emer"enc& situation, for

e!ample &ou can usebac5up copies to restore dama"ed primar& super

bloc5.

4ollo#in" command displa&s primar& and bac5up superbloc5 location

on 0dev0sda1$

F dumpe6fs 0dev0hda1 Y "rep -i superbloc5

J K 8hat is the load a#era$e o the ser#er and 8hat is an

acceptable -er#er


26/87

1'&} 6an we ha#e two apache ser#ers ha#in$ di #ersions?

9es, &ou can have t#o different apache servers on one server, but the&

cant listen to the same port at the same time.Normall& apache listens

to port 2 #hich is the default TT port. The second apache version

should listen to another port #ith the /isten option in httpd.conf, for

e!ample to port


27/87

N,- -7:B7:

1} 7plain this entry .shared

192(1&+(1('.2%%(2%%(2%%('sync/rw

allo#s all s&stems #ith


28/87

N4( stands for Net#or5 4ile (&stem. N4( #as ori"inall& developed b&

(un Eicros&stems in the


29/87

The e!portfs command is used to maintain the current table of

e!ported file s&stems for N4(.

1"} 7plain command @.usr.sbin.eports EA?

It #ill flush ever&thin" out of the 5ernels e!port table. An& clients that

are active #ill "et ne# entries added b& mountd #hen the& ma5e their

ne!t re*uest.

1%} 8hich option is used with eports command to display

the current eport list/ also displays the list o eport

options?

e!portfs -v


30/87

2'} 8hat do you understand by @nsstat Eo all E23"A

command?

It #ill (ho# all information about all versions of N4(.

21} 8hat do you understand by @nsstat Kns Kser#er E3A

command?

It #ill sho# statistics for N4( version 1 server.

22} 6an N,- share mounted on 8indow X0 and Mustiy your

answer?

No, 'indo# X operatin" s&stem doesnt support nfs protocol.

23} 192(1&+(1(%1J.data is eported by N,- -er#er and i want

to add this N,- share to client .etc.stab ile( 5ow you will

add this entry in .etc.stab ile?

F device mount-point fs-t&pe options dump fsc5order


31/87

2&} 8hat is @portmapA?

The portmapper 5eeps a list of #hat services are runnin" on #hat

ports. This list is used b& a connectin" machine to see #hat ports it

#ants to tal5 to access certain services.2)} 5ow you will check @portmapA ser#ice is runnin$ or not?

rpcinfo -p

2+} I am unable to mount a N,- share( 5ow will you trace

out the reason?

4irstl&, chec5 that &ou have permissions to mount nfs share or not.

Chec5 0etc0e!ports file.

(econdl& &ou can "et %C error$ ro"ram Not %e"istered =or anotherR%CS error

4or this chec5 &our N4( server and portmap service runnin" or not b&

Rrpcinfo -pS

29} 6an I modiy eport permissions without needin$ to

remount clients in order to ha#e them take eect?

9es. The safest thin" to do is edit 0etc0e!ports and run Re!portfs -rS.

,0 -7:B7:

1} 5ow to deny speciic users access to the ,0 ser#er?

To den& specific users access to the 4T server, add their usernames to

the 0etc0vsftpd0 ftpusers file. :& default, s&stem users such as root and

nobod& are included in this list.

2} 6an we create lo$s or tp authenticated sessions?

9es, If the !ferlo"[enable directive in vsftpd.conf is set to 9(, file

transfers usin" the 4T protocol are lo""ed to 0var0lo"0!ferlo".

Information such as a time stamp, I address of the client, the file


32/87

bein" transferred, and the username of the person #ho authenticated

the connection is included in the lo" entr&.

3} 8hat is meanin$ o maLclients parameter?

Ea!imum number of clients that can connect at one time. If set to 2,

the number of clients is unlimited.

"} Gn which port B-,0 ser#er works ?

4T uses t#o ports, 62 and 6


33/87

%ed at nterprise /inu! ? or 4D%A includes the vsftpd 4T

service.

vsftpd-6.2.?-


34/87

'hen enabled, vsftpd attempts to maintain lo"in sessions for each

user throu"h lu""able Authentication Eodules =AE.

3} Is there any way to monitor clients connected to

#stpd?9es. 'e actuall& have t#o sli"htl& different methods to

monitor vsftpd clients. 4irst, ma5e sure &ou have enabled the confi"

option, Rsetproctitle[enable>9(S li5e in our e!ample above and

restart &our vsftpd server. Then run the command R#atch ps -Cvsftpd

-o user, pid, stime, cmdS to #atch the processes includin" ip,

username and actions li5e idle or data retrieval.


35/87

:IN uses 0etc0named.conf as its main confi"uration file, the

0etc0rndc.conf file as the confi"uration file for name server control

utilit& rndc, and the 0var0named0 director& for zone files and the li5e.

2} 8hat is >IN;?

:IN stands for :er5ele& Internet Name omain #hich is the most

commonl& used omain Name (&stem =N( server on the Internet.

3} Gn which #ersion o bind u ha#e worked?

:IN 7

"} 8hat is the role o ;N-?

A N( server, or name server, is used to resolve an I address to a

hostname or vice versa.

%} Gn which port ;N- ser#er works?

N( servers use port ?1 b& default. Incomin" and out"oin" pac5ets

should be allo#ed on port ?1. Also allo# connections on port 76< if&ou confi"ure a li"ht#ei"ht resolver server. The N( control utilit&,

rndc, connects to the N( server #ith TC port 7?1 b& default. If &ou

are runnin" rndc on the name server, connections on this TC port

from localhost should be allo#ed. If &ou are runnin" rndc on

additional s&stems, allo# connections to port 7?1 =or #hatever port

&ou have chosen to confi"ure from these additional s&stems.

&} 8hat is round robin ;N-?

%ound robin N( is usuall& used for balancin" the load of

"eo"raphicall& distributed 'eb servers. 4or e!ample, a compan& has

one domain name and three identical home pa"es residin" on three

servers #ith three different I addresses. 'hen one user accesses the


36/87

home pa"e it #ill be sent to the first I address. The second user #ho

accesses the home pa"e #ill be sent to the ne!t I address, and the

third user #ill be sent to the third I address. In each case, once the I

address is "iven out, it "oes to the end of the list. The fourth user,therefore, #ill be sent to the first I address, and so forth.

)} 8hat is Name -er#er?

A name server 5eeps information for the translation of domain names

to I addresses and I addresses to domain names. The name server is

a pro"ram that performs the translation at the re*uest of a resolver or

another name server.

+} 8hat is 0rimary name ser#er or primary master ser#er?

rimar& name server0primar& master is the main data source for the

zone. It is the authoritative server for the zone. This server ac*uires

data about its zone from databases saved on a local dis5. The primar&

server must be published as an authoritative name server for the

domain in the (DA resource record, #hile the primar& master server

does not need to be published.

9}8hat is -econdary name ser#er.sla#e name ser#er?

(econdar& name server0slave name server ac*uires data about the

zone b& cop&in" the data from the primar& name server =respectivel&

from the master server at re"ular time intervals. It ma5es no sense to

edit these databases on the secondar& name servers, althou"h the& are

saved on the local server dis5 because the& #ill be re#ritten durin"

further cop&in".

1'} what is :oot name ser#er?


37/87

%oot name server is an authoritative name server for the root domain

=for the dot. ach root name server is a primar& server, #hich

differentiates it from other name servers.

11} what is -tealth name ser#er?

(tealth name server is a secret server. This t&pe of name server is not

published anhere. It is onl& 5no#n to the servers that have its I

address staticall& listed in their confi"uration. It is an authoritative

server. It ac*uires the data for the zone #ith the help of a zone

transfer. It can be the main server for the zone. (tealth servers can be

used as a local bac5up if the local servers are unavailable.

I12} 8hat do you mean by @:esource :ecordsA?

Information on domain names and their I addresses, as #ell as all

the other information distributed via N( is stored in the memor& of

name servers as %esource %ecords =%%.

13} 7plain @


38/87

There is al#a&s onl& one (DA record in the file, and it is placed at the

be"innin" of the file of authoritative resource records.

1&} what is @4 :ecordA?

A =Address records assi"n I addresses to domain names of

computers. The I address cannot have a dot at the end.

1)} 7plain @6N4C7 :ecordA?

(&non&ms to domain names can be created usin" CNAE records.

This is often referred to as creatin" aliases for computer names.

1+} 8hat are @5IN,G and X :ecordsA?

IN4D and TXT records are for information onl&. An IN4D record

has t#o items in its data part. The first item is information about

hard#are, and the second one is information about soft#are. A TXT

record contains a "eneral data strin" in its data part.

!ample $ test.com IN (DA ^ ^ mail IN A


39/87

2'} 7plain @0: :ecordsA?

A ointer %ecord =T% is used to translate an I address into a

domain name.

6


40/87

-U port 4 ser#er ypes ?

+ rimar& omain Controller =C + :ac5up omain Controller

=:C + A( omain Controller

K8 'hich protocol (AE:A server uses (E:, #hich stands for (erver

Eessa"e :loc5, is a protocol for sharin" files, printers, serial ports,and communications abstractions such as named pipes and mail slots

bet#een computers.

)} 5ow ;oes a 8orkstation ind its ;omain 6ontroller?

There are t#o different mechanisms to locate a domain controller$ one

method is used #hen Net:ID( over TC0I is enabled and the other

#hen it has been disabled in the TC0I net#or5 confi"uration.'here Net:ID( over TC0I is disabled, all name resolution involves

the use of N(, broadcast messa"in" over U, as #ell as Active

irector& communication technolo"ies.


41/87

+} 6an -amba >e a >ackup ;omain 6ontroller to an N"

0;6?

No. The native NTJ (AE replication protocols have not &et been full&

implemented.

9} 5ow ;o I :eplicate the smbpasswd ,ile?

%eplication of the smbpass#d file is sensitive. It has to be done

#henever chan"es to the (AE are made. ver& users pass#ord

chan"e is done in the smbpass#d file and has to be replicated to the

:C. (o replicatin" the smbpass#d file ver& often isnecessar&.As the

smbpass#d file contains plainte!t pass#ord e*uivalents, it must not

be sent unencr&pted over the #ire. The best #a& to set up smbpass#d

replication from the C to the :C is to use the utilit& rs&nc. rs&nc

can use ssh as a transport. ssh itself can be set up to accept onl& rs&nc

transfer #ithout re*uirin" the user to t&pe a pass#ord.As said a fe#

times before, use of this method is bro5en and a#ed. Eachine trust

accounts #ill "o out of s&nc, resultin" in a bro5en domain. This

method is not recommended. Tr& usin" /A instead.1'} 6an -amba ully replace my 8indows N ser#er that is

not a 0rimary ;omain 6ontroller 0;6?

(amba can completel& serve files and printers to 'indo#s, Oust as a

'indo#s NT server #ould.

11} 6an -amba replaces my 8indows N 0;6?

Not completel&. (amba domain control capabilities for a 'indo#s 7!

client are solid and complete, and so these clients #ould probabl&

never 5no# the difference. The domain control support for 'indo#s

NT06222 clients is still bein" developed. Currentl&, enou"h has been

implemented to allo# a 'indo#s NT client to Ooin a (amba-controlled

domain, but there is more to domain control than that. The most


42/87

conspicuous absence is the lac5 of support for 'indo#s NT trust

relationships and the (AE replication protocol used bet#een NT Cs

and :ac5up omain Controllers =:Cs.

12} 8hat 60 and U;0 ports re!uired or Net>IG- o#er

60.I0 use?

The N:T name service uses port


43/87

share, the client is issued a tree connection I =TI. The TI is used

in all re*uests to access files contained in the resource to #hich the

TI refers. In this #a& (E: protocol #or5s.

1"} 5ow man sections samba coni$uration ile smb(con

contains?

smb.conf file contains three sections.

user1)} 5ow you will #eriy that your smb(con ile doesnt ha#e

any mistakes and misspellin$s?

Rtestparm S tool that verifies the s&nta! of a confi"uration

file=smb.conf.

testparm -s smb.conf

1+} 8hat is the use o @smbclientA command?

RsmbclientS is used to displa& the list of shares on &our server. This

verifies that smbd is runnin" and functionin" correctl&. The -/ option

instructs smbclient to enumerate the shares on the server rather than

actuall& connectin" to one. The -N s#itch instructs smbclient to use an


44/87

anon&mous lo"in rather than the lo"in name of the current user.

smbclient -/ localhost -N

Antother use of RsmbclientS command to connect the samba share.

smbclient 00Qserver30Qshare3 -U Qusername3


45/87

The most li5el& cause is that ('AT is not listenin" to connections, or

&ou have used the #ron" U%/ in tr&in" to connect to ('AT. ('AT

usuall& lives behind port 72


46/87

It #ill define the "roup id to be used for all file access in the place of

the users primar& "roup.

(ubmitted :&$-Larun mail-I$ -5umar.varun


47/87

domain trust relationships. This is impossible #ith server-level

securit&. The second reason is that, under server-level securit&, each

smbd process must 5eep an open connection #ith the authentication

server. This can drain a 'indo#s NT C *uic5l&. Under domain-level securit&, this connection is maintained onl& lon" enou"h to

perform the validation, thus conservin" valuable resources. The final

reason is that, as a domain member, the (amba server has access to

much more information about user accounts, #hich can be used to

automate the creation and deletion of user accounts upon demand.

33} what is nmbd daemon?

This daemon handles all name re"istration and resolution re*uests. It

is the primar& vehicle involved in net#or5 bro#sin". It handles all

U-based protocols. The nmbd daemon should be the first command

started as part of the (amba startup process.

3"} 8hat is smdb daemon?

This daemon handles all TC0I-based connection services for file-

and print-based operations. It also mana"es local authentication. It

should be started immediatel& follo#in" the startup of nmbd.

3%} 8hat is winbindd daemon?

This daemon should be started #hen (amba is a member of a

'indo#s NTJ or A( domain. It is also needed #hen (amba has trust

relationships #ith another domain. The #inbindd daemon #ill chec5

the smb.conf file for the presence of the idmap uid and idmap "id

parameters. If the& are found, #inbindd #ill use the values specified

for UI and I allocation. If these parameters are not specified,

#inbindd #ill start but it #ill not be able to allocate UIs or Is.

3&} 7plain the parameter @wins support O DesA used

in smb(con?

If the (amba server #as confi"ured to provide 'IN( support =R#ins


48/87

support > 9esS, then the 'IN( server is able to provide name

resolution for all of the hosts that are not listed in the 0etc0hosts file or

#ithin the N(. Ea5in" this adOustment in the Name (ervice (#itch

confi"uration file =0etc0nss#itch.conf allo#s the /inu! s&stem to*uer& the 'IN( server for local name resolution. This saves manual

adOustments to host files.

3)} 5ow to automate -C> share mountin$ durin$ system

startup?

Add smb share entr& in 0etc0fstab file.

00I[A%(([D4[(%L%0(hared 0shared smbfs noauto,defaults

2 2

3+} how to start and stop samba ser#er?

0etc0init.d0smb restart

-7NC4I< -7:B7:

1} 5ow to start sendmail ser#er ?

service sendmail restart2} Gn which ports sendmail and senmail with --< works ?

:& default, (endmail uses TC and U port 6? for non-encr&pted

transfers. If the (endmail server is confi"ured to use ((/ for

encr&ptin" email sent and received, it uses port JK?.

3} 7plain use o @trustedEusersA ile ?

/ist of users that can send email as other users #ithout a #arnin"

includin" s&stem users such as apache for the Apache TT (erver.

"} 7plain the use o @localEhostEnamesA ile ?


49/87

If the email server should be 5no#n b& different hostnames, list the

hostnames in this file, one line per hostname. An& email sent to

addresses at these hostnames is treated as local mail. The

4ATU%=_use[c#[file` option must be enabled inthesendmail.mc file for this file to be referenced.

%} eplain the use o .etc.aliases ile ?

0etc0aliases, can be used to redirect email from one user to another. :&

default, it includes redirects for s&stem accounts to the root user. It

can then be used to redirect all email for the root user to the user

account for the s&stem administrator.

&} 6an we use --< 7ncryption with -endmail ?

9es, (endmail can be confi"ured to encr&pt email sent and received

usin" ((/ =secure soc5ets la&er.

)} 8hat is -endmail?

(endmail is an ETA, meanin" it accepts email messa"es sent to it

usin" the (ET protocol and transports them to another ETA email

server until the messa"es reach their destinations. It also acceptsemail for the local net#or5 and delivers them to local mail spools, one

for each user.

+} 8hat is the role o CU49} 8hich are the important

coni$uration iles or -endmail ser#er??

An EUA =Eail User A"ent #ith access to the mailbo! file, directl& or

throu"h a net#or5 file

s&stem, can read messa"es from the dis5 and displa& them for the

user. This is "enerall& a console or #ebmail application runnin" on the

server.

The 0etc0mail0 director& contains all the (endmail confi"uration files,

#ithsendmail.cf and submit.cf bein" the main confi"uration files.


50/87

The sendmail.cf file includes options for the mail transmission a"ent

and accepts (ET connections for sendin" email. The submit.cf file

confi"ures the mail submission pro"ram.

1'} 5ow to coni$ure sendmail to accept mail or local

deli#ery that is addressed to other hosts?

Create a 0etc0mail0local-host-names file. ut into that file the

hostnames and domain names for #hich sendmail should accept mail

for local deliver&. nter the names #ith one hostname or domain

name per line. And also ma5e sure that (endmail confi"uration file

should contain Ruse[c#[fileS option.

dnl /oad class ># #ith other names for the local host4ATU%=_use[c#[file

11} 8hen an or$ani*ation stores aliases on an


51/87

the desired aliases, rebuild the aliases database file #ith the

ne#aliases command.

13} Dou ha#e been asked to create a sendmail coni$uration

that sends all local mail to a mail hub/ while directly

deli#erin$ mail addressed to eternal systems(

Create a sendmail confi"uration containin" the EAI/[U: define to

identif& the mail rela& host for local mail. Use the /DCA/[U(%

command to e!empt the root users mail from rela&in".

dnl efine a rela& server for local mail define=_EAI/[U:,

_smtp.test.com dnl Users #hose mail is not passed to the mail hub/DCA/[U(%=root

%ebuild and reinstall sendmail.cf, and then restart sendmail.

1"} 5ow to coni$ure multiple mail !ueues?

m5dir 0var0spool0m*ueue0*ueue.< m5dir

0var0spool0m*ueue0*ueue.6 m5dir 0var0spool0m*ueue0*ueue.1

chmod M22 0var0spool0m*ueue0*ueue.< chmod M22

0var0spool0m*ueue0*ueue.6 chmod M22 0var0spool0m*ueue0*ueue.1

Add the UU[I% define to the sendmail confi"uration to use the

ne# *ueue directories.

dnl eclare the *ueue director& path define=_UU[I%,

_0var0spool0m*ueue0*ueue.G

1%} 5ow to disable certain -C0 commands?

Add the conf%ILAC9[4/A( define to the sendmail confi"uration toset rivac& Dptions that disable un#anted, optional (ET commands.

ere #e #ill disables the XN, L%49, L%:, and T%N commands.

dnl isable XN, L%49, L%: and T%N

define=_conf%ILAC9[4/A(, _noe!pn,novrf&,noverb,noetrn

%ebuild and reinstall sendmail.cf, and then restart sendmail.


52/87

1&} In which -endmail coni$uration ile we ha#e to make

chan$es?

#e #ill ma5e the chan"es onl& in the sendmail.mc file, and the

chan"es #ill be moved into the sendmail.cf file for us.

1)} 8hen -endmail dispatches your email/ it places the

ser#ers hostname behind your username/ which becomes

the @rom addressA in the email ie(

userPmail(test(com(>ut we want to use the domain name

and not the hostname?

define=_confDEAIN[NAE,

_test.comdnl 4ATU%=_rela&[entire[domaindnl

1+} 8hat does .etc.mail.access ile contains?

The access database =R0etc0mail0accessS is a list of I addresses and

domainnames of allo#able connections.

4ATU%=_access[db,_hash -TQTE43 -o 0etc0mail0access.dbdnl

and cat 0etc0mail0access

localhost.localdomain %/A9 localhost %/A9


53/87

21} 8hich anti#irus you ha#e inte$rated with sendmail ?

ClaimAL

22} 8hat is 6lama#ECilter?

Clamav-Eilter is a tool to inte"rate sendmail and clamAL antivirus.

23} 8hich coni$uration iles are re!uired to inte$rate

sendmail and 6laim4B anti#irus?

milter.conf and clamav-milter

2"} 5ow to test sendmail inte$ration with 6laim4B?

"rep Eilter 0var0lo"0maillo"9ou have to "et follo#in" t&pe of messa"es.

sendmail$ Eilter add$ header$ X-Lirus-(canned$ ClamAL version

2..6, clamav-milter version 2..6 on mail.test.com sendmail$

Eilter add$ header$ X-Lirus-(tatus$ Clean

2%} 8hich tool you ha#e used to block spammin$?

(pamAssassin

2&} 8hat does @.etc.mail.A directory contains?

The 0etc0mail0 director& contain all the (endmail confi"uration files,

#ithsendmail.cf and submit.cf bein" the main confi"uration files.

2)} 7plain the use o .etc.mail.relayEdomains ile?

The 0etc0mail0rela&-domains file is used to determine domains from

#hich it #ill rela& mail. The contents of the rela&-domains file should

be limited to those domains that can be trusted not to ori"inate spam.

2+} 8hat is the name o spamassassin coni$uration ile?

0etc0mail0spamassassin0local.cf


54/87

29} 5ow to check mail ueue o sendmail?

0usr0lib0sendmail -bp

or

mail*3'} 5ow to use m" macro processor to $enerate a

new sendmail(c?

mJ 0etc0mail0sendmail.mc 3 0etc0mail0sendmail.cf

C4I< -7:B7:

1} 8hich !mail process use @concurrecylocalA control ile?

*mail-send

2} 8hat is maildir?

Eaildir is a mailbo! format created b& an :ernstein to address the

shortcomin"s of the mbo! format. A maildir mailbo! is a director&containin" three subdirectories, ne#, cur, and tmp. ach messa"e in a

maildir mailbo! is in a separate file in one of the subdirectories,

dependin" upon its status$ ne# is for unread messa"es, cur is for

messa"es that have been seen, and tmp is for messa"es in the process

of bein" delivered.

3} 8hat is procmail?

procmail is a popular Eessa"e eliver& A"ent =EA. The function of

an EA is to accept a messa"e from the ETA for a specific user or

mailbo!, and deliver the messa"e accordin" to the users desires.

procmail can be used to RfilterS messa"es b& the content of various

header fields or the bod& of the messa"e.


55/87

"} 8hich =roups and Users are re!uired to start C4I rootP !it bin0m&s*ladmin

reload

The ne!t time &ou lo" in, &ou #ill use &our ne# pass#ord

9} 8here is the data stored in a Cy-< database?

E&(/ uses files to store data. These files are under the

data0databasename director&, #here databasename is the name of the


81/87

database. There are three file t&pes$ .I(E, .4%E, and .I(. The .4%E

file contain the table schema. The .I( is the file that actuall& holds

the data. The .I(E file is the file that provides *uic5 access bet#een

the t#o of them.

1'} 7plain the terms @mys!limportA/ @mys!ldumpA/

@mys!ladminA and @mys!lcheckA?

m&s*limport for importin" data files, m&s*ldump for ma5in" bac5ups,

m&s*ladmin for server administration, and m&s*lchec5 for chec5in"

the inte"rit& of the database files.

11} 5ow you will determine the options which are used bymys!l?

Fm&s*l +help

12} 5ow you will determine the #ersion o Cy-


82/87

9ou as5ed for help about help cate"or&$ RContentsS

4or more information, t&pe help Qitem3, #here Qitem3 is one of

the follo#in" cate"ories$

AdministrationColumn T&pes

ata efinition

ata Eanipulation

4unctions

eo"raphic features

Transactions

1&} 8hat is Cy-< uery >rowser?

The E&(/ uer& :ro#ser is a "raphical tool desi"ned to provide a

user friendl& environment in #hich to construct and e!ecute (/

statements.

1)} 7plain @4UGLIN6:7C7NA attribute?

AUTD[INC%ENT attribute ma& be added to an inte"er column

definition to create a column for #hich E&(/ automaticall&"enerates a ne# se*uence number each time &ou create a ne# ro#.

There ma& be onl& one AUTD[INC%ENT column per table, the

column must be inde!ed, and the column must be defined as NDT

NU//.

1+} 8hat this command @mys!ladmin status #ariablesA will

do?

This command #ill displa& a brief status messa"e, follo#ed b& the list

of server s&stem variables.

19}7plain @6576F 4>


83/87

structure and contents. It #or5s for E&I(AE and Inno: tables. 4or

E&I(AE tables, it also updates the inde! statistics. If the table is a

vie#, CC@ TA:/ verifies the vie# definition.

2'} 7plain @:704I: 4>


84/87

2%}8hat is the use o @IN,G:C4IGNL-657C4

;atabaseA?

The IN4D%EATIDN[(CEA database provides access to database

metadata.IN4D%EATIDN[(CEA is a Rvirtual databaseS in the

sense that it is not stored anhere on dis5. :ut li5e an& other

database, it contains tables, and its tables contain ro#s and columns

that can be accessed b& means of (/CT statements.

2&} 8hat is @binary backupA?

A binar& bac5up is a cop& of the files in #hich database contents are

stored. Cop&in" these files preserves the databases in e!actl& the sameformat in #hich E&(/ itself stores them on dis5. %estoration

involves cop&in" the files bac5 to their ori"inal locations. Techni*ues

for ma5in" binar& bac5ups include file cop& commands.

2)} 8hat is @tet backupA?

A te!t bac5up is a dump of database contents into te!t files.

%estoration involves loadin" the file contents bac5 into databases b&

processin" them throu"h the server. Techni*ues for ma5in" te!tbac5ups include the (/CT INTD DUT4I/ (/ statement,

m&s*ldump, and E&(/ Administrator.

2+} 5ow you will $rant the -7


85/87

3'} 7plain the command @-5G8 =:4N- ,G:

rootPlocalhostVA

It #ill sho# the account has "lobal, database-level, and table-level

privile"es.

GC64 400 -7:B7:

1} I stored a cookie on the browserV why cant I see it?

4irst, chec5 to ma5e sure &ou spelled the coo5ie name correctl&. Ne!t,

ma5e sure the bro#ser has coo5ies enabled. Also, if &ou specified a

root path for the coo5ie, ma5e sure that the ( or servlet readin" the

coo5ie is in that path. %emember, too, that if &ou dont "ive the coo5ie

a specific e!piration time, the coo5ie #ill vanish #hen the user shuts

the bro#ser do#n.

2}8hy is a new obQect created whene#er I call

QspJuse>ean?9ou probabl& for"ot to specif& a scope for the bean.

%emember, the default scope for a bean is pa"e, and all beans #ith

pa"e scope disappear #hen the pa"e finishes e!ecutin".

3} 8hen do I use ( and when do I use W?

Althou"h &ou can use these operators interchan"eabl&, it is a "ood idea

to use an operator that indicates the 5ind of data bein" accessed. 4or

e!ample, if &ou are accessin" a bean propert&, use the . operator. If &ou

are accessin" a map value or an arra& inde!, use the ;B operator. There

are plent& of times #hen &ou brea5 this rule, especiall& in cases #here

&ou #ant a map to loo5 li5e it is a bean, &ou #ant thin"s to ma5e sense

to the ne!t person #ho reads &our code. 9ou ma& 5no# the t&pes of all

the variables, but the ne!t person ma& not.

"}5ow do I coni$ure omcat to work with II- and N


86/87

4ollo# the standard instructions for #hen the isapi[redirector.dll

Confi"ure II( to use Rinte"rated #indo#s securit&S

In server.!ml, ma5e sure &ou disable tomcat authentication$

QConnector port>S227j enable/oo5ups>SfalseS redirectort>SJJ1jprotocol>SA0SfalseS 03

%}7plain the concepts o omcat -er#let 6ontainer(

+ Tomcat (ervlet Container is a servlet container. The servlets runs in

servlet container. + The implementation of ava (ervlet and the ava

(erver a"es is performed b& this container. + rovides TT #eb

server environment in order to run ava code. + %educes "arba"ecollection + Native 'indo#s and Uni! #rappers for platform

inte"ration

&} 8hy do I $et a 6lassNot,ound7ception when I try to use

the -hoppin$6art class?

The ( en"ine probabl& cant see the class in its classpath. Tomcat

uses the s&stem classpath, so if (hoppin"Cart.class is visible

some#here in the s&stem classpath, the& should see it.

)}8hat is omcat?

Tomcat is a ava (ervlet container and #eb server from a5artha

proOect of Apache soft#are foundation. A #eb server sends #eb pa"es

as response to the re*uests sent b& the bro#ser client. In addition to

the static #eb pa"es, d&namic #eb pa"es are also sent to the #eb

bro#sers b& the #eb server. Tomcat is sophisticated in this respect, as

it provides both (ervlet and ( technolo"ies. Tomcat provides a "ood

choice as a #eb server for man& #eb applications and also a free

(ervlet and ( en"ine. Tomcat can be used standalone as #ell as

behind other #eb servers such as Apache httpd.


87/87

+} 8hat is Masper?

asper is a pro"ram to read the .class files in binar& format. This

pro"ram can "enerate A(CII files , #hich can be used alon" #ith

asmin Assembler. asper is intended for "eneratin" input into a class

file bro#ser #hich can produce the hierarch& of inheritance and

composition maps from the .class files.

9}6an I set Ma#a system properties dierently or each

webapp?

No. If &ou can edit Tomcats startup scripts, &ou can add R-S options

to ava. :ut there is no #a& to add such properties in #eb.!ml or the

#ebapps conte!t.

MJ

M?

linux interview questions & answers

Documents