Data Encapsulation and Communications Flashcards
What is Encapsulation?
the process of breaking a message into packets; adding control and other information; and then transmitting the message through the transmission medium.
What is the first step in data encapsulation?
The application layer prepares the data to be sent through the network
What is the second step in the encapsulation process?
The Transport layer breaks the data into pieces called segment, adding sequencing and control information
What is the third step in the encapsulation process?
The internet layer converts the segments into packets, adding logical network and device addresses
What’s the fourth step in the encapsulation process?
The Link Layer converts the packets into frames, adding physical device information and a frame check sequence (FCS) footer for error detection. it also converts the frames into bits for transmission across the transmission media
What is the purpose of the Address Resolution Protocol (ARP)?
To dynamically find the address of a computer you would want to talk to
What is the first step in IP-based communications?
The data to be transferred is encapsulated on the sending host by moving from the top layer of the TCP/IP or OSI model to the bottom
What is the second step in IP-based communications?
The data is transmitted on the network medium
What is the third step in IP-based communications?
If necessary, the data is transferred to various routers, which forward the data to the appropriate network.
What is the fourth step in IP-based communications?
The data is delivered to the destination host
What is the fifth step in the IP-based communications?
The data received is de-encapsulated on the destination host by moving from the bottom layer of the TCP/IP or OSI model to the top.
What is a star topology network?
uses a hub or switch to connect all network connections to a single physical location
What is mesh network topology?
when there are multiple paths between any two nodes on a network
What is a hybrid network topology?
when two or more types of network topologies are connected with each other
Describe Carrier Sense Multiple Access/Collision Detection (CSMA/CD)
means that every node on the network must monitor the bus for a period of no activity before trying to send a message on that bus (carrier sense)
What is the maximum cable length for UTP Ethernet T implementation
100 meters
How many hosts can be supported on a single subnet?
support a maximum of 1024 hosts on a single subnet
What is a frame
a unit of data that is ready to be sent on the network medium
What is a preamble?
a set of alternating ones and zeros terminated by two ones (11), which mark it as a frame.
What is a destination address
identifies the receiving host’s MAC address.
What is the source address
identifies the sending host’s MAC address.
What is the type in a ethernet frame
is two bytes and specifies the network/internet layer protocol being used.
What is a packet
contains the information that needs to be transmitted from one host to the other.
What is the pad in an ethernet frame
Ethernet frames are sized between 64 and 1518 bytes. If the frame is smaller than 64 bytes, the sending NIC places junk data in the pad to make it the required 64 bytes.
What is the frame check sequence (FCS)
helps verify that the frame contents have arrived uncorrupted
What is a hub
provides a central connecting point for multiple media segments on the same subnet. When a hub receives a signal, the hub sends out the signal to all the ports on the hub. Hubs operate in half-duplex mode because the path between devices is shared.
What is a bridge
connects two segments within the same subnet. Bridges learn which side a host resides on by copying the MAC address of the source device and placing it into the MAC address table. The port number at which the frame entered is also recorded in the table and associated with the source MAC address.
What is a switch
a multiport bridge. It provides the same functionality, but with a higher port density. In addition, switches provide features that cannot be found in bridges
What does a layer 2 switch do
operates at the Data Link layer of the OSI model to process frames within a single physical network segment.
What does a layer 3 switch do
provides all the functionality of a layer 2 switch but also provides routing functionality at the Network layer of the OSI model
What layer of the OSI model is a router on?
Layer 3 device
How does a router work?
forward packets through an internetwork by maintaining routing information in a database called a routing table
What is a routing table?
contains the address of all known networks and routing information about that network
What does the the routing table store?
Interface Routing path Next hop Route metric (cost) Route timeout
What is convergence
used to describe the condition when all routers have the same (or correct) routing information.
What functionality do routers provide over bridges and switches?
Support multiple routing protocols for better flexibility.
Provide more features than switches or bridges, such as flow control, error detection, and congestion control.
Provide multiple links between devices to support load balancing.
Can connect different network architectures together. For example, a router can be used to connect an older Token Ring network to an Ethernet network.
What layer of the OSI model is a Access Point on?
Layer 2
What is a WLAN controller?
used to connect multiple APs through wired links
What does a WLAN controller do?
Manages all of the APs that are connected to it. Configuration changes are made on the controller, then pushed out to all connected APs.
Usually provides DHCP services to dynamically assign IP addressing information to wireless clients.
Connects the wireless network to the internal wired network.
Routes wireless traffic from the wireless network to the internal wired network (and vice versa).
What is a firewall?
a software-based or hardware-based network security system that allows or denies network traffic according to a set of rules.
How do firewalls decide what traffic comes and goes through the network
By ACL- Access Control List
What is a Next Generation Firewall (NGFW)
combines a traditional firewall with other network device filtering functionalities such as an application firewall.
Name some the advantages a NGFW has
Is application-aware
Tracks the state of traffic based on layers 2 through 7
Utilizes an intrusion protection system (IPS)
Tracks the identity of the local traffic device and user ( LDAP, RADIUS, Active Directory)
Can be used in bridged and routed modes
Utilizes external intelligence sources
