Networks

Question 1

1st OSI layer

Answer 1

Physical

Bit stream going through the wires
Cables connected to devices
Hubs

Question 2

2nd OSI layer

Answer 2

Data Link

Error-free data frame transfer over physical
Frames (envolopes)
Switches
Mac addresses
ARP

Question 3

What does OSI stand for?

Answer 3

Open Source Interconnection

Question 4

3rd OSI layer

Answer 4

Network

Control operation of the subnet, decide which physical path to take
Packets (letters)
Routers, Subnets, default gateways
IP/ICMP

Question 5

4th OSI layer

Answer 5

Transport

Message transfer guarantee, in order, without duplicates or losses
TCP/UDP
Message ACK
Message Segmentation

Question 6

5th OSI layer

Answer 6

Session

Session establishment and termination
Logical ports
Sockets

Question 7

6th OSI layer

Answer 7

Presentation

Format the data to feed into the Application layer (if needed), mostly controlled by the Operating System
Data/image compression
Character set translation
Data encrypt/decrypt
SSL TLS

Question 8

7th OSI layer

Answer 8

Application

Whatever the user/app wants to use and do
SMTP/HTTP

Question 9

What are the OSI layers

Answer 9

Application
Presentation
Session
Transport
Network
Data Link
Physical

Question 10

How many versions of SSL/TLS?

Answer 10

SSL 1.0 (unpublished), 2.0, 3.0

TLA 1.0, 1.1, 1.2, 1.3 (draft )

Question 11

How many versions of HTTP?

Answer 11

HTTP 0.9, 1.0, 1.1, 2.0

Question 12

What is the purpose of the ARP protocol?

Answer 12

Provide a mapping between the MAC and IP addresses in a network

Question 13

Number of bits in IPv4 and IPv6 addresses

Answer 13

32 for IPv4

128 for IPv6

Question 14

Format and size of an IPv4 address

Answer 14

4 octects of bits

from 0.0.0.0 to 255.255.255.255

Question 15

Format and size of an IPv6 address

Answer 15

8 groups of 4 hexs
from 0000:0000:0000:0000:0000:0000:0000:0000
to FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF

Question 16

Loopback address in IPv4

Answer 16

127.0.0.0/8 -> 127.0.0.1 to 127.255.255.255

Question 17

Loopback address in IPv6

Answer 17

0000:0000:0000:0000:0000:0000:0000:0001
or
::1

Question 18

Routing schemes
1 -> 1
1 -> *
1 -> n
1 -> ?

Answer 18

unicast
broadcast
multicast
anycast

Question 19

Main DNS record types

Answer 19

A record (name -> IPv4)
AAAA record (name -> IPv6)
CNAME record (name -> name)
PTR record (IPv? -> name) DNS reverse lookup
SOA record, Start of Authority