Chapter 1 Flashcards
How many layers in ISO OSI?
7
What are the layers in ISO OSI
7 = application
6 = presentation
5 = session
4 = transport
3 = network
2 = data link
1 = physical
What does OSI stand for?
Open Systems Interconnection
what does ISO refer to and where is the real name derived from
International Standards organization and it comes from the Greek language and mean same
What is a protocol?
Set of conventions (agreed-upon way of doing things
What is the OSI model used for today?
It is used as a reference model
What are the common protocols in the 7th layer?
HTTP SMTP and POP3
What does POP3 stand for and what is it used for
Post Office Protocol version 3, used to retrieve email from a server
Give an HTTP example to retrieve a index.htm file from www.xx.co.za
GET /index.htm HTTP/1.1
What are some standards used in Layer 6?
XML HTML MIME
What does layer 4 enable?
process-to-process communication
what is the purpose of layer 3?
It performs routing functions. most commonly it just shows the next router on the path
what is the purpose of layer 2?
Provide mean to transfer data between network entities and to detect/correct errors that may occur in physical layers
What is layer 1 made up of?
Since it is the physical layer it is made up of copper cables and so on
List all the bodies that issue standards:
ISO, IEEE, IETF, IANA,ICANN,W3C,CCITT,NIST
What type of oriented protocols does the application layer have?
User-oriented protocols
Most common architecture in this course?
client-server
On what layer is FTP?
Layer 7
What is the problem with client-server architecture?
Client always initiates communication
What does P2P (Peer-to-Peer) enable?
different participants to work as equals
by what RFC is SMTP defined by?
RFC 5321
What is an alternative to POP3?
IMAP4 (Internet Message Access Protocol
What is the most well known tool to see traffic on a network?
WireShark
What does DNS stand for?
Domain name system
What is a TLD?
Top level domain
What are the types of TLD’s
gTLD, ccTLD,sTLD
what does gTLD stand for
generic TLD
what does ccTLD stand for?
country code TLD
what does sTLD stand for?
Sponsored TLD
What does SCADA system do?
Controls industrial equipment from a single point in a facility
What was X25 used for?
Routes network across international waters
When did tim burners lee invent the www?
1990
why are standards needed?
So that computers can communicate with each other
what does set type=a do?
it is Used to specify that you want to query for the Address (A) records associated with a domain name.
What is the difference between FQDN(fully qualified domain name) and a normal domain name
Normal = refer to a name within some current domain. FQDN = specifies domain starting at the TLD down to the domain name of interest
what does set type=ns do?
tells nslookup that we want a pointer to a name server rather than the address associated with the domain
what does nslookup do?
Show how Domain Names is translated to IP address
What is a zone file?
A file that stores the Domain Info. Defines Resource records. authorative source.
How do you determine the owner of a domain?
Enter whois “xx.co.za” command
By who is IANA operated by?
ICANN (Internet Corporation for Assigned Names and Numbers)
Who has authority at the root of the DNS?
IANA (Internet Assigned Numbers Authority)
what does a CNAME(canonical name) do?
Assigns an alias to a domain name
In the ISO each layer provides services for the layer directly … it. Each layer uses the services provided by the layer directly … it
above. below
Is the OSI model a specific set of protocols?
No. it is just a reference model
what port does ssh use
22
What port does SMTP use
25
What port does HTTP use
80
What port does telnet use?
23
What port does FTP control use?
21
What port does FTP data use?
20
Why is FTP still used?
There are many functions that can be used to make file handling easier
What is passive connection
———>
actor
———-> server
else
———–>
actor
<———- server
bottom = control connection
top = data connection
What can layer 6 do?
Translate.(converting) XML HTML MIE ARPA
What does RFC stand for?
Request for Comments
What is the main idea for transport layer 4?
Have a path between processes that participate in the convo. It can also throttle data that goes across it
What is the purpose of layer 3?
to route the messages
What does layer 2 do?
marks the beginning and end of a message
