lab terms Flashcards
Transport layer
This layer has two important functions - distinguishes individual connections at the same device using ports and also controls the speed of data flow (co-called flow control)
Does the UDP provide connection-oriented communication?
No
Which layer performs routing?
Network layer
Devices that are completely independent from any protocol
Hub, repeater
Local area network (LAN)
‘Local’ refers to the networks of relatively small size, which usually connect end stations together and have connection to Wide area network
What are the three main functions of TCP?
- Guarantee data delivery in a correct order
- Distinguish individual connections
- Data flow control
DHCP(Dynamic host configuration protocol)
DHCP is a service for automatic configuration of network interfaces in one segment of local network. DHCP works only for IPv4 addresses (DHCPv6 is used for IPv6)
Can the individual layers be changed without change in functionality of neighboring layers?
Yes
Define the mask
A mask is a 4-byte number that binary starts with a sequence of ones which is followed by a sequence of zeros. The size of both sequences is arbitrary. The mask is paired with a specific IP address
3 protocols of network layer
IPv4, IPv6, IPX-SPX
Each network service expects to communicate on a specific…
port
Are routers able to interconnects networks of a completely different types? If yes, why?
Yes, they can, because physical router ports, in contrast with switch and hub, can have different physical and link layers
How does TCP distinguish individual connections and services?
By using source and destination port, which are represented by a 16-bit numeric value
Does TCP guarantee data delivery in a correct order?
Yes
Switch
Switch is a device used for station interconnection in one local network segment. This device basically only forwards data frames between its ports based on the MAC address
Physical layer
The first layer of ISO/OSI model that takes care of data transfer thriugh physical medium
Are there any switches that work on the network layer?
Yes, Layer 3 switches
Can different LANs use the same private IP addresses ranges?
Yes, because LANs use private IP addresses which are unique only within particular LAN
How to check that a device can communicate with different networks?
The device has its own simple routing table. If everything is OK, the routing table contains both special entries
Which architecture does DHCP have?
Client-server
Name the ways of classifying IPv4 and IPv6
Class and classless, for IPv6 it is only classless addressing
What happens to the link layer header while routing?
It is discarded and replaced by the new one
What are the phases of TCP connection?
Establishment, data transfer, termination
On which layer does the switch work?
The Link Layer
Pure virtual interfaces lack this layer (loopback)
Physical layer
When the switches can drop the packets?
In case of congestion
Why repeaters and hubs are slow?
Because their principle allows only one network interface to communicate within the network segment
Does NAT change port numbers?
Yes
A device connected to a network through a network interface is
a single-port router from a certain point of view. Instead of forwarding data between networks, it only sends and receives data from the network
Firewall
By a firewall, we mean a router that, in addition to routing, allows to apply a security policy (such as packet filter or proxy server)
Dynamic NAT
We talk about dynamic translation if we translate a range of IP addresses into one IP address
At which layer of ISO/OSI model TCP takes place?
On the trasport layer
What is defined on second layer of ISO/OSI model?
MAC address
What is dynamic routing?
When the routing table can be filled automatically using routing protocols(RIP, OSPF)
Is there any difference between manual and automatic IP address from communication point of view?
No, there is no difference (It is just some kind of address assigned to the interface)
How to find a MAC address in OS unix?
ifconfig -a
Network address translation (NAT)
Network Address Translation (NAT) is a complementary service of router. Basically, it is a packet filter that changes packet headers for network and transport layers based on set rules
2 protocols of transport layer
TCP, UDP
On which layer of ISO/OSI model does UDP take place?
On the transport layer
The hardware part of the interface
For example, the port to which we connect the cable + combined electronics
How is the default gateway entry added to the routing table?
Manually
How splitting of address space works?
We assign a so-called network address to each segment. This address determines, in addition to the identification, the total range of IP addresses that belong to that segment. The IP address is then divided into two parts: the network address and the interface address in that network
What is the difference between router ports and switch/hub ports?
Physical router ports can have, in contrast with switch and hub, different physical and link layers. Routers then are able to interconnect networks of a completelly different types (for example wired and wireless)
Can you delete the entries of directly connected networks from the routing table?
Typically, you cannot delete such entry from the routing table by standard means
Network card
Physical layer in a network interface that is always implemented by hardware
How to prevent private addresses getting outside of their local network?
Network address translation(NAT)
Which endpoints define the TCP connection?
Client IP address, client port number, server IP address, server port number
How do repeater and hub differ?
- Hub is multi-port, the repeater is 2-port
- Hub can divide electrical signal
What is a static routing?
When entries in the routing table are manually entered by the administrator
Who performs routing?
Routing is performed by a router that contains a routing table
Example of purely hardware network interface
Repeaters
Ranges of private IP addresses:
10.0.0.0/8
172.16.0.0/12
192.168.0.0/16
Can MAC addresses be propagated through the router? Why?
No, they can’t. Because during routing the original link layer header is discarded and replaced by the new one
Static NAT
This is the translation of one IP address into one IP address
Where the broadcast MAC is used?
When we need to send data to all output ports of a switch and it is also used in ARP and DHCP
What is routing?
Routing is a packet forwarding mechanism between individual network segments based on a routing table