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49 Cards in this Set
- Front
- Back
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What are the seven layers of the OSI protocol stack? briefly explain each |
1. Physical - Physical cable and electrical signalling 2. Data Link - Error free (kind of) media access for datagrams. 3. Network - Provides a path through the network data 4. Transport - Reliable (usually) flow of datagrams between nodes. 5. Session - Synchronizes dialogue between two programs 6. Presentation - Converts data between two formats used by programs. 7. Application - Applications that use the network or something... |
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What are layers 1-4 and layers 5-7 of the OSI protocol stack referred to as? |
Layers 1-4: transmission - how data moves through the network. Layers 5-7: understanding - how data appears to applications and users. |
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What are three transmission attributes? |
Bandwidth Electrical Interference (noise) Attenuation (signal decay) |
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What is the difference between baseband and and broadband? |
Baseband - One channel (most LAN connections) Broadband - Multichannel (i.e. cable) |
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Name the three access methods |
Carrier sense, multiple access and collision detection (CSMA/CD) Token Passing (Token Ring) Point-to-point (PPP) (bae caught me SLIPin) |
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Name three media types
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Coaxial
Twisted Pair Optical Fibre |
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Which parts of the OSI protocol stack are considered "gateway" protocols |
layers 4-7 |
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What do the following do? (give an example of each) Physical gateway Datalink gateways Network gateways |
Physical gateway - Allows network beyond standard cable length limits ex. a repeater, hub Datalink gateways - Uses link-level address to determine passing of packets ex. a bridge, switch Network gateways - Transmits packets based on IP address ex. router Fun fact: UNIX systems can act as routers if packet forwarding is enable though this is not recommended (let routers do router and UNIX do ... UNIX stuff) |
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Name the IP protocol family
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TCP: Transmission Control Protocol UDP: User Datagram Protocol IPv4: Internet Protocol ICMP: Internet Control Messaging Protocol ARP: Address Resolution Protocol Fun fact: a list of protocols can be found on UNIX under /etc/protocols |
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What address is used at the link level? and what is the UNIX command to view the current machines address? |
MAC(and chese) address lanscan or ifconfig |
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What are the different classes of IP addresses |
Class A - 1-126 Class B - 128-191 Class C - 192-223 Class D - 224-239 (multicast) Reserved/Experimental - 240-255 |
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What are the private networks that are not allowed on the public IP range and how are they connected to the internet? |
10.0.0.0 172.16.0.0 - 172.31.0.0 192.168.0.0 - 192.168.255.0 They connect using NAT |
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What are subnets? |
Subnets break up networks into smaller more manageable chunks. A group in a subnet can communicate without having to pass through a router. |
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What are subnet masks? |
Subnet masks determine the subnet lengths (I know this shish) |
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What is the command to view or set a host name in UNIX? |
hostname or uname -n |
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Name the three host naming systems |
–NIS: »Flat name space »Does more than just hosts: users, groups, protocols, home directories,etc. –DNS: »hierarchical »Internet standard »Does mainly hostnames and email routing –NIS+: »combines features of NIS and DNS, adding secure authentication |
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What are the five main shells in UNIX? |
Bourne Shell Bash (Bourne again) Shell C Shell T Shell Korn Shell |
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What are several features that make UNIX popular? |
UNIX is: - portable - multiuser - multitasking - networking - organized file system - device independence - utilities- services |
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What are the three different computing environments used in UNIX? |
- stand-alone : personal environment - time-sharing : multiple users connected to a computer - client/server: users get clients and computing is shared |
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What is the kernel and shell? |
The kernel contain the OS's process control and resource management The shell receives and interprets commands |
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what are the different wildcards that can be used when browsing the file system |
? : replaces any single character [...] : any single character set * : 0 or more character |
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what command is used to change directories and what is used to view files in the current directory |
cd - change directory ls - view files in current directory (-l for long list) |
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what can be used to change to home directory and what can be used to change to parent directory |
~ : home directory .. : parent directory |
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what is the difference between relative pathname and absolute pathname |
a relative pathname is a path that is contained in the current directory and does not begin with '/'an absolute pathname is a path that starts from the root and starts with a '/' |
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what is the difference between a directory and a file |
a directory cannot be run and contains other files and directoriesa file contains content that can be viewed or run |
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what is the command to remove a directory and make a new directory |
rmdir : remove directorymkdir : makes new directory(bonus: directory cannot be removed unless empty) |
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what are the commands to copy, move and remove files |
cp : copy mv : move / rename rm : remove |
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what command can be used to change permission on a file |
chmod |
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what is the syntax for chmod |
chmod -option mode file/directory example: $ chmod u=rwx file.doc $ chmod a+w this.txt |
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what are the octal values for chmod |
r w x 4 2 1 4 = r--, 2 = -w-, 1 = --x, 6 = rw- etc... user group all example 776 file1.doc = u: rwx, g: rwx, a: rw- |
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what is the command to change owner and change group |
chown: change owner (must be superuser) chgrp: change group |
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what command can be used to find the current shell |
echo $0 |
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what are the three standard streams |
input (0), output (1) and error (2) |
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how do you use a file as the input instead of the keyboard |
command < file |
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how do you copy the output to a file (3 types) |
command > file (new file) command >| (overwrite file) command >> file (append file) |
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how do you copy errors to a file (3 types) |
command 2 > file (new) command 2 >| (overwrite) command 2 >> (append) |
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what does the pipe operator do and how do you call it |
pipe (|) takes the output of the previous command and uses it as input for the next command ex: $echo 3+3 | bc > 6 |
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how do you call a sequence of commands on the same line |
commands can be executed in sequence by using ";" between each command |
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what are the conditional commands that can be used |
&& - and ||- or |
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what is needed to use meta keys as normal characters |
\ |
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how do you start a background job |
command& |
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how can you stop, start, kill and move a background job to the foreground |
stop 'job number' - suspend bg 'job number' - resume kill 'job number' - kill fg 'job number' - move to foreground |
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what is the difference between job number and process ID |
job numbers are for commands are different for each user whereas processes are for the entire OS |
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what is UNIX written in |
C |
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what happens when you try to copy a file to one that already exists |
the existing file is overwritten |
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how can you tell if a path name is relative or absolute |
absolute path names have a / at the beginning whereas relative starts with a folder or file name |
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should you start your file names with a (.)? why? |
no because normally hidden files start with a dot |
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How do you generate a random number in korn shell |
RANDOM=$$ Every time you echo RANDOM it will generate a new number between 0 and -32767 |
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How do you create an alias? How do you remove an alias? |
alias 'command' - creates an alias unlais 'command' - removes alias name |
