Network Fundamentals Flashcards
1
Q
What is a Host?
A
Device at the edge of the network that’s creating the data and receiving
2
Q
Everything Between sending and receiving is called?
A
Network Infrastructure
3
Q
What is a logical topology?
A
How devices appear connected to the user
4
Q
What is a Bus Topology?
A
All devices are aware of each other on the network and talk directly
5
Q
What is a Star Topology and what are they connected to?
A
All devices connected to an access device. IE a switch
6
Q
What is a Ring Topology?
A
Big loop where devices can see each other and can talk to each other.
7
Q
What does fully meshed mean?
A
Everyone connected to the network can talk with each other
8
Q
What is partially meshed?
A
The topology is segmented to where only certain subnets are able to talks with each other.
9
Q
What is the 3 layer Topology design?
A
- Access Layer: Device that gives the Frontline (computers, laptops) connectivity.
- Distribution Layer: Routers mainly, network infrastructure devices, sub divide networks and routing
- Core Layer: network backbone, high speed network connection
10
Q
What is a firewall?
A
Inline system that enforce an access control policy between various network segments defined as security zones.
11
Q
What is a protocol?
A
Rules of operation
12
Q
What are the 7 layers of the OSI model and what acronym do you use to remember them?
A
- Physical, Please
- Data Link, Do
- Network, Not
- Transport, Throw
- Session, Sausage
- Presentation, Pizza
- Application, Away
13
Q
What happens in the application layer(7)?
A
- Interacts with user applications
- provides initial network connection for use applications.
- Manages the application connection between host
14
Q
What all happens in the presentation layer (6)?
A
- Performs encryption within an application.
- Ensures that data is presented correctly
- performs translation of cross-platform standards that may be understood by the local machine. IE .jpg to .png and .wav to .mp3
15
Q
What all happens in the session layer (5)?
A
- Helps establish session with reserved port numbers.
- Session identifier is assigned
- Tracks connections between host and remote computer/servers
16
Q
What are the well known port ranges?
A
0 - 1023
17
Q
What is the registered port range?
A
1024 - 65535
18
Q
What is an ephemeral port?
A
Random one time port that’s used in a session. IE: having chrome open with multiple tabs to the same site. Each tab has it’s own ephemeral port as an identifier.
19
Q
What is the HTTP port?
A
Port 80
20
Q
What is the HTTPS port?
A
Port 443
21
Q
What is the DNS port?
A
Port 53
22
Q
What are the FTP ports?
A
Port 20 and 21
23
Q
What is the Telnet port?
A
Port 23
24
Q
What layer does TCP run at?
A
Layer 4, transport layer
25
What all happens at the transport layer (4)?
1. Fragmentation
2. Sequencing and reassembling
3. Windowing, buffering, congestion avoidance
4. Error Correction
26
What is TCP?
Transmission control Protocol
1. Connection Oriented - Verifies destination exist first
2. Reliable
3. Protocol #6
27
What is UDP?
User Datagram Protocol
1. Connection-less - just sends the data regardless
2. Unreliable
3. Protocol #17
28
What all happens at the network layer (3)?
1. Segmentation of network topology into logical portions
2. Logical addressing
3. Path Discovery and Selection
29
What is a routed protocol and examples of them?
Protocols that are used for identification.
1. IP
2. IPS
3. AppleTalk
Routed - Where I am on the network and where the data needs to be sent
30
What is a routing protocol and examples of them?
Protocols that get the best path for the routed protocols
1. EIGRP
2. OSPF
Routing - Learns about about other networks and where they are and the best path to it
31
What all happens in the data link layer(2)?
1. Media Access Control - The rules of putting stuff on the wire and when it's ok to start or stop.
2. Link layer addressing - On this link/wire how do we address ourself?
3. Error Checking
32
What devices are used at the data link layer?
Switches and bridges
33
What all happens at the physical layer (1)?
1. Electrical signals carried over cable.
34
What devices are used at the physical layer?
Hubs
Repeaters
NIC's
Cabling
35
What is a PDU?
Protocol Data Unit - the final structured data unit created by an OSI layer
36
How are PDU's received?
PDU's that are created at a certain layer are meant to be received by the same layer on the receiving device
37
What is a layer 4 TCP PDU called?
Segment
38
What is a layer 4 UDP PDU called?
Datagram
39
What is a layer 3 PDU called?
Packet
40
What is a layer 2 PDU called?
Frame
41
What is encapsulation?
As each layer receives a PDU from the layer above it headers are added
42
What is decapsulation?
As each layer receives a PDU from the layer below it headers are then inspected and removed.
43
What layer does IPv4 Reside at?
Layer 3 (network Layer)
44
What is needed for a layer 3 protocol to be considered routed?
It has to be able to give a node (your computer/laptop) an address and that address has to be part network and part host and also has to provide a destination address.
45
A single 1 or 0 is called?
Bit
46
What are 8 bits called?
Byte
47
What happens when a sent packet is too large for a protocols MTU?
It can be fragmented down to an acceptable size. Each fragment is given a number in the identification field that it know that it was fragmented and also what order to put things back together in.
48
What helps put the packet fragments back in order if too large for a MTU?
Flag and fragment offset
49
What is time to live?
How many times a packet can pass a router before being discarded. Each router pass decrements the number by 1 until it reaches 0
50
What are some common IP Protocols and their values?
ICMP - 1
IGMP - 2
TCP - 6
UDP - 17
51
What does a checksum do?
checks if there has been a problem with the packet to see if it's been modified or not
52
What is a payload?
The layer 4 segment behind the header
53
What is a Unicast?
One to one communication
54
What is a multicast?
Has a special multicast address, one to many communication.
55
What is a broadcast?
One to all communication. Talks to all devices on that wire.
56
What is DHCP?
Dynamic Host Configuration Protocol. Dynamic assignment of IP information
57
What port does DHCP utilize?
Port 67 and 68
58
What is a static IP?
An Ip that is manually configured and not learned automatically
59
What is DNS?
Domain Name Service that is used to resolves website names to ip address. IE Google.com to 74.125.21.113
60
What port does DNS use?
Uses UDP port 53
61
What is the DNS Process?
Host sends a DNS A-Record Query to the DNS server looking for a resolution the the address that was entered. The DNS Server responds with a A-Record Query response
62
How is the DNS server IP learned?
Through DHCP
63
What are the pre-dominant protocols used at layer 4?
TCP and UDP
64
What is a TCP Sync?
IP packet that is sent to the destination address to make sure that the destination exist
65
What is the 3-way TCP handshake?
1. Originator sends the TCP Sync
2. Destinatin replies with TCP Sync + Acknowledgement bit
3. Originator sends Acknowledgement bit back after receiving
66
What is the Class A address range?
Ranges from 0.0.0.0 to 127.255.255.255
67
If the first bit in an address is set to 0 it is what class address?
Class A
68
What is the Class B address range?
Ranges from 128.0.0.0 to 191.255.255.255
69
If the first two bits in an address are set to 10 what class is it considered?
Class B
70
What is the Class C address range?
Ranges from 192.0.0.0 to 223.255.255.255
71
If the first 3 bits of an address are set to 110 what class is it considered?
Class C
72
What is the Class D address range?
Ranges from 224.0.0.0 to 239.255.255.255
73
If the first 4 bits of an address are set to 1110 what class is it considered?
Class D
74
What is the Class E address range?
Ranges from 240.0.0.0 to 255.255.255.255
75
If the first 5 bits of an address are set to 11110 what class is it considered?
Class E
76
What is a subnet mask?
A number that helps identify the host and network portion of an address and also what range of IP's that can be used
77
What is the default Class A subnet mask?
255.0.0.0
78
What is the default Class B subnet mask?
255.255.0.0
79
What is the default Class C subnet mask?
255.255.255.0
80
Ip addresses that are leased out are known as?
Public IP Addresses
81
IP addresses that are unregistered and may have overlap from company to company are known as?
Private IP Addresses
82
Where do IP's come from?
Internet Assign Numbers Authority
83
What is the Private Class A IP range?
10.0.0.0 through 10.255.255.255
84
What is the Private Class B IP range?
172.16.0.0 through 172.31.255.255
85
What is the Private Class C IP range?
192.168.0.0 through 192.168.255.255
86
What is IP summarization?
Aggregating multiple subnets into a single network advertisement that does not break classful boundaries
87
What is IP supnetting?
Aggregating multiple subnets into a single network advertisement that does break classful boundaries
88
IPv6 addresses are represented in what format?
Base 16
89
What is an IPv4 Checksum's purpose?
To protect the header of IPv4 data packets against data corruption
90
What does the term dual stacked mean?
That both IPv4 and IPv6 are in use.
91
How can a IPv6 address be dynamically derived?
Through EUI-64
92
What is the unique identifier for IPv4 called?
Host Bits
93
What is the unique identifier for IPv6 called?
Interface-ID's
94
What is EUI-64?
The special rules and protocols used to come up with an IPv6 address using the host's MAC Address
95
What characters does EUI-64 add to turn a MAC address into a 64 bit number?
FF:FE
Example:
MAC: aaaa:bbbb:cccc
EUI-64 Unique Identifier: aaa:bbFF:FEbb:cccc
96
When EUI-64 is used a certain bit is changed to the opposite of what it was originally, what bit is that and where is it located?
Global/Universal Local Bit and it is located in the first 'word' of a MAC address and is the 7th bit in that word.
97
What is an IPv6 Link Local Address and what does it begin with?
Automatically assigned address (Similar to IPv4 169.254.x.x address) that ALWAYS BEGINS with FE80::/10
98
What are the last bits of a Link Local Address?
The last 64 bits is the MAC Address with FF:EE in the middle
Example:
MAC: aaaa:bbbb:cccc
Link Local: FE80:aaaa:bbFF:FEbb:cccc
99
Link Local Addresses can never be?
Routed, they have to stay on the network that they originated from.
100
With a Global Unicast Address the high-level 3 bits are set to what, the first 3 bits?
They are set to 001 and begin with the number 2 or 3
Example:
2000::/3
101
What is a Global Unicast Address?
The unique IPv6 address used for communicating with other networks
102
What is a Unique Local Address and it's format?
Similar to the IPv4 Private address where it's not globally routed.
Begins with FC00::/7
103
What is a Multicast Address and how is it formatted?
An address to try and talk to anyone that is currently listening on that wire
104
What is an Any Cast Address?
2 or more nodes using the same IPv6 address used to manage load-balancing
105
What does NDP stand for?
Neighbor Discovery Protocol
106
What do NDP and ICMPv6 do?
Responsible for address autoconfiguration of nodes, discovery of other nodes on the link, determining the addresses of other nodes, duplicate address detection.
107
What messages types were added with ICMPv6?
Neighbor Solicitation
Neighbor Advertisement
Router Solicitation
Router Advertisement
108
What does ICMPv6 stand for and a common use of it?
Internet Control Messaging Protocol
A common use would be the "Ping" command
109
What it called when a host check to see if anyone has their link local address?
Duplicate Address Detection
110
What layer is ICMPv6?
Layer 4 and above
111
What is the IPv6 all host multicast address?
FF02::1 - All host
112
What is the IPv6 all router multicast address?
FF02::2 - All Routers
113
What is the ICMPv6 Process?
1. NIC card creates a link local address using FE80::/10
2.Next it has to check if that link local address is unique so it sends out a neighbor solicitation packet.
Source: Link Local
Destination: Solicited node multicast
3.If there was someone with that link local there would be a neighbor advertisement. Very Rare
4. Sends out a ICMPv6 Router Solicitation packet.
Source: Link Local Address
Destination: FF02::2
5. Router Advertisement is returned with the routers Link Local Address
6. Then the PC would use EUI-64 to create a global address now.
7. Finally a Duplicate Address Detection is sent out to see if that address is currently on the wire or not.
114
What is in the body of a router advertisement and why is it important?
All the prefixes that are currently on that interface and it would all the pc to know that SLAAC could be used to generate a global address
115
What is ARP?
Address Resolution Protocol for IPv4 ONLY!!!
116
When is IPv4 ARP used?
When trying to resolve someone in your subnet
117
When is IPv4 ARP useful?
When trying to reach someone on your network and you know their layer 3 address but not their layer 2 address
118
What is the IPv4 ARP Process?
```
1. An ARP Request is created with:
Source: Host IP
Destination: Router IP
Source: Host MAC
Destination: (Broadcast MAC address) ffff:ffff:ffff:ffff
```
2.An ARP Response is made with the Routers layer 2 MAC address and IP Address
119
What is a Solicited Node Multicast Address?
IPv6 multicast address valid within the local-link
120
What is the Solicited Node Multicast Address prefix?
FF02:0:0:0:0:1:FF /104
or
FF02::1:FF /104
121
Where are the last 24 bits of a Solicited Node Multicast Address pulled from?
The interface ID
Ex:
Interface ID: aaaa.bbbb.cccc
Solicited Node Multicast Address: FF02:0:0:0:0:1:FFbb.cccc
122
What is Solicited Node Multicast Address used for?
Layer 3 to Layer 2 resolution
