2.5 Given a scenario, install & configure basic wired/wireless SOHO networks Flashcards
1
Q
What is a protocol?
A
Rules for structured data communication among networked hosts
2
Q
What are protocols often designed for?
A
Working together as a protocol suite
Most networks have converged on the use of the TCP/IP suite.
3
Q
Why is the TCP/IP suite divided into layers?
A
To better understand the function of each protocol
4
Q
In the TCP/IP, what does each lower protocol do?
A
Encapsulate data from higher-layer protocols
As data moves down the protocol stack, lower-layer protocols add their own headers before transmitting it
5
Q
List the 4 layers of the TCP/IP suite
A
- Application
- Transport
- Internet
- Link (Network Interface)
6
Q
Purpose of TCP/IP’s link layer?
A
Put frames onto the physical network
7
Q
Which TCP/IP layer does not contain a TCP/IP protocol?
A
Link (Network interface) layer
8
Q
What is used at the TCP/IP’s link layer?
A
LAN protocols & media
i.e. Ethernet or Wi-Fi
9
Q
Where does communication on the TCP/IP’s link layer take place?
A
Only on a local network segment
Not between different networks
On an Ethernet or Wi-Fi segment, data at the link layer is packed into frames; node interfaces are identified by a MAC address
10
Q
Purpose of TCP/IP’s Internet layer?
A
Address & routes packets across across a network of networks
(the Internet)
11
Q
What is an “end system host”?
A
Device that can communicate on an IP network
i.e. PC, laptop, mobile device, server, etc.
12
Q
What’s required to transmit IP packets over a physical/data link layer?
Like Ethernet or Wi-Fi
A
Mechanism to encapsulate IP packets within data link layer frames
13
Q
What mechanism encapsulates IP packets within data link layer frames?
A
ARP
14
Q
Meaning of ARP?
A
Address Resolution Protocol
15
Q
What does ARP do?
A
Queries the MAC address associated with an IP address
16
Q
2 types of delivery IP can provide?
A
Unreliable & connectionless delivery
A packet may be lost, delivered out of sequence, duplicated, or delayed
17
Q
Purpose of TCP/IP’s Transport layer?
A
Manages multiple connections for application layer protocols
18
Q
How is the TCP/IP’s Transport layer protocol implemented?
A
Via TCP or UDP protocol
19
Q
What kind of packet delivery does TCP provide?
A
Connection-oriented packet delivery
TCP identifies & recovers lost or out-of-order packets, enhancing IP reliability. This is crucial for TCP/IP application protocols to prevent data errors.
20
Q
What kind of packet delivery does UDP provide?
A
Connectionless packet delivery
UDP provides unreliable packet delivery
21
Q
Which Transport layer protocol is faster?
A
UDP
22
Q
Why is UDP faster than TCP?
A
Doesn’t send extra data for reliable connections
23
Q
When is UDP used over TCP?
A
In time-sensitive applications where packet loss is tolerable
i.e. speech or video. Rather than causing the app to crash, they would just manifest as a glitch in video or a squeak in audio
24
Q
What does the TCP/IP’s Application layer contain?
A
Protocols that perform a high-level function
Rather than simply addressing hosts & transporting data
25
What are Application protocols used for?
Managing network hosts & services
| services like web & email
26
What does each application protocol use to connect clients to a server?
TCP or UDP ports
27
What are the 2 most important fields in an IP packet?
Source & destination IP address
28
2 versions of IP?
- IPv4
- IPv6
29
How long are IPv4 addresses?
32 bits
## Footnote
In its raw form, it appears as 11000000101010000000000000000001. These 32 bits can be divided into 4 groups of 8 bits, known as "octets". The IP address is rearranged as 11000000 10101000 00000000 00000001, which is easier to read in dotted decimal notation (192.168.0.1).
30
What is the range of an IPv4 address?
0.0.0.0 to 255.255.255.255
| However some addresses are not permitted or are reserved for special use
31
What 2 pieces of information do IPv4 addresses provide?
- Network ID
- Host ID
32
What does the Network ID in an IPv4 address identify?
The network to which a device belongs
| The network ID is common to all hosts on the same IP network
33
What does the host ID in an IPv4 address identify?
A host within an IP network
34
What distinguishes the host & newtork ID of an IPv4 address?
Network prefix
35
What is a network prefix?
32-bit value with contiguous 1s identifing the network part of an IP address
## Footnote
i.e. a prefix with 24 bits means: `11111111 11111111 11111111 00000000`. The prefix can be written in slash notation in the form `/24`
36
What is the dotted decimal expression of a network prefix called?
| i.e. 255.255.255.0
Subnet mask
37
What does each binary `1` indicate in a subnet mask?
The corresponding bit in the IP address belongs to the Network ID
## Footnote
A subnet mask, like `255.255.255.0` (binary: `11111111.11111111.11111111.00000000`), works with an IP address like `192.168.1.100` (binary: `11000000.10101000.00000001.01100100`). Wherever the subnet mask has a 1, that part of the IP address is for the network, and where it has a 0, it's for the host. So, in this case, the network ID is 192.168.1.0, and the host ID is 0.0.0.100.
38
# What does this slash notation mean?
`192.168.0.0/24`
The first 24 bits represent the network ID
| The network ID would be `192.168.0`.
## Footnote
The last `.0` is reserved as the network address, and `.255` is often reserved as the broadcast address. So, for example, `192.168.0.1` to `192.168.0.254` would be assignable host addresses within the `192.168.0.0/24` network
39
What is slash notation often used for?
| i.e. 192.168.0.0/24
To refer to network IDs
| i.e. `192.168.0.0/24` refers to an IP network
40
What is a subnet mask often used for?
| i.e. 255.255.255.0
Host configuration dialogs
## Footnote
i.e. `192.168.0.1/255.255.255.255` refers to a host address on that IP network
41
What happens when a host sends a packet via IPv4?
IPv4 compares source & destination IP address against the sending host's subnet mask
42
What does IPv4 do if the masked portion of source & destination addresses don't match?
Host assumes the packet must be routed to another IP network
43
What is the default gateway?
IP address of a router interface
| Most hosts are configured with a default gateway parameter
44
What do hosts use default gateways for?
To forward packets to other networks
45
What is a requirement for a host to use a gateway address?
Both must be on the same IP network
46
What happens if hosts have a private IPv4 address?
Not allowed to route traffic over the public Internet
47
What is the use of private IPv4 addresses confined to?
Private LANs
48
3 private IPv4 address ranges?
- Class A
- Class B
- Class C
49
Class A private IPv4 address range?
10.0.0.0 to 10.255.255.255
50
Class B private IPv4 address range?
172.16.0.0 to 172.31.255.255
51
Class C private IPv4 address range?
192.168.0.0 to 192.168.255.255
52
What is the typical subnet mask for Class A private IPv4 addresses?
255.0.0.0
| The network prefix for this is `/8`
53
What is the typical subnet mask for Class B private IPv4 addresses?
255.255.0.0
| The network prefix for this is `/16`
54
What is the typical subnet mask for Class C private IPv4 addresses?
255.255.255.0
| The network prefix for this is `/24`
55
2 ways hosts with private address can access the Internet?
- Via router with public addresses
- Via proxy server
## Footnote
Proxy server can fulfill requests for Internet resource on behalf of clients
56
How does a router convert between private & public IP addresses?
Using NAT
57
Meaning of NAT?
Network Address Translation
58
Minimum configuration a host needs to communicate on an IPv4 network?
IP address & subnet mask
## Footnote
This minimum setup isn't very usable. More configurations are needed for a host to fully utilize a network or the Internet
59
What addresses cannot be assigned to a host in an IP network?
The first or last address
## Footnote
i.e. in the IP network `192.168.0.0/24`, `192.168.0.0` is the first address & `192.168.0.255` is the last address
60
What is the first address in an IP network used for?
## Footnote
i.e. in the IP network `192.168.0.0/24`, `192.168.0.0` is the first address
To identify the network itself
61
What is the last address in an IP network used for?
## Footnote
i.e. in the IP network `192.168.0.0/24`, `192.168.0.255` is the last address
To broadcast to all hosts
62
What is the valid host address range in `192.168.0.0/24`?
`192.168.0.1` to `192.168.0.254`
## Footnote
The first & last address arent included because theyre reserved for other uses
63
2 other parameters that make a host fully functional in an IPv4 network?
| Besides an IP address & subnet mask
- Default gateway
- DNS server addresse(s)
64
What happens if a host is not configured with a default gateway?
Host can only communicate within the LAN
65
What is the primary DNS server address usually configured as?
The same as the gateway address
## Footnote
The router would be configured to forward DNS queries to a secure resolver. Often, 2 DNS server addresses are specified for redundancy
66
What does static IP addressing require?
Admin to enter config. info for each computer/host
## Footnote
Admin must keep track of which IP addresses have been allocated to avoid issuing duplicates
67
What happens if a host shifts to a new subnet with static addressing?
Admin must manually reconfigure it
## Footnote
Manually configuring IP addresses for every node in a large network is time-consuming and error-prone, risking communication disruptions
68
What are static IP addresses typically only assigned to?
Systems with a dedicated functionality
## Footnote
i.e. router interfaces or application server that need to use a fixed IP address
69
What is an alternative to static network configuration?
DHCP server
## Footnote
A host can receive its IP address, subnet mask, default gateway, & DNS server addresses
70
What occurs if a host can't reach a DHCP server for network setup?
Uses an APIPA/link-local address
71
Meaning of APIPA?
Automatic Private IP Addressing
72
What is the range of an APIPA/link-local address?
`169.254.0.1` to `169.254.255.254`
73
What can a host with an APIPA/link-local address do?
Communicate with other hosts on the LAN using an APIPA/link-local address
74
What ***CAN'T*** a host do with an APIPA/link-local address?
Can't reach other networks or communicate with DHCP hosts
| Meaning hosts with a valid DHCP lease
75
Which vendor uses the term ***APIPA*** rather than "link-local"?
Microsoft
## Footnote
Other vendors & open-source products use the term "link local"
76
What may a host do if it can't reach a DHCP server but doesn't use APIPA/link-local addressing?
May leave the IP unconfigured or use the `0.0.0.0` IP address
## Footnote
it would use `0.0.0.0` to indicate that the IPv4 address of the interface is not known
77
What interfaces does a SOHO router have?
- Public digital modem interface
- Private Ethernet interface
## Footnote
The public digital modem is used to connect to the ISP. Ethernet is for LAN
78
What must both interfaces of a SOHO router be configured with?
## Footnote
Both interfaces = Public digital modem interface & private Ethernet interface
An IP address & subnet mask
79
Which SOHO router interface is used by hosts as the default gateway parameter?
LAN interface
## Footnote
This address is also used to access the router's web management interface (i.e. `https://192.168.0.1`)
80
What is a router's public interface IP address determined by?
ISP
## Footnote
It must be a valid public IP address. Internet service providers sometimes assign a static IP or offer it as an option for an additional fee. Otherwise, the public interface gets dynamically configured using the ISP's DHCP server.
81
3 ways to tell if an IPv4 address is public?
- Not from a private range
- Doesn't start with a 0
- Not a value of `224.x.y.z` or above
| Private range like 10.x.y.z, 172.16-32.x.y, or 192.168.0-255.x
## Footnote
The values `224.x.y.x` & above is reserved for other types of addressing schemes
82
How to configure a SOHO router?
- Connect computer to router
- Load the device's management URL on browser
| Computer can be connected to router via RJ45 port or wireless network
## Footnote
The management URL could be an IP address or host/domain name (i.e. `http://192.168.0.1` or `http://www.routerlogin.com`
83
What to do if you can't connect to a router's device management URL?
## Footnote
The management URL could be an IP address or host/domain name (i.e. `http://192.168.0.1` or `http://www.routerlogin.com`
Verify if the computer's IP address matches the router's LAN IP range
84
How many bits are in a IPv6 address?
128
85
What can one hexadecimal digit express?
4-bit binary value
| i.e. hex `A` = `1010`
86
How is an IPv6 address constructed?
is divided into 8 double-byte values separated by colons
| `2001:0db8:0000:0000:0abc:0000:def0:1234`
87
2 ways to shorten an IPv6 address?
- Ignore leading `0`'s
- Replace contiguous series of `0`s with a double colon (`::`)
## Footnote
`2001:0db8:0000:0000:0abc:0000:def0:1234` --> `2001:db8::abc:0:def0:1234`
88
How is the network & host ID identified in an IPv6 address?
- First 64 bits = Network ID
- Last 64 bits = Host ID
## Footnote
i.e. in `2001:0db8:0000:0000:0abc:0000:def0:1234`, the Network ID is `2001:0db8:0000:0000` & the Host ID is `0abc:0000:def0:1234`
89
Why dont IPv6 address need a subnet mask?
The Network & host portions are a fixed size
90
What does prefix notation in IPv6 represent?
| i.e. `/32`
The length of the routing prefix in bits
## Footnote
The length of the network prefix in IPv6 determines whether addresses belong to the same network. ISPs often assign /48 prefixes to customers for private networks, allowing up to 65,346 subnets to be configured.
91
2 types of IPv6 addresses IPv6 interfaces may be configured with?
- Global address
- Link-local address
| IPv6 interfaces are more likely to be configured with multiple addresses
## Footnote
While it's possible to configure IPv6 addresses statically, most hosts obtain a global & link-local address via local router
92
What are IPv6 global addresses used for?
Communicating over the Internet
| This is the equivalent to IPv4 public addresses
93
What hex digit do IPv6 global addresses start with?
`2` or `3`
| i.e. `2001:0db8:85a3:0000:0000:8a2e:0370:7334`
94
What are IPv6 link-local addresses used for?
Communication between devices on the same LAN
95
What do IPv6 link-local addresses start with?
`fe80::`
96
What is SLAAC?
| SLAAC = StateLess Address Auto Configuration
IPv6 method where devises self-assign addresses without a server
| Central server like DHCP server
97
How do IPv6 hosts obtain a global & link-local address via router?
Through SLAAC
98
What network configuration do IPv6 hosts not need?
Default gateway
99
3 reasons IPv6 uses the Neighor Discovery (ND) protocol?
## Footnote
NDP is a protocol used in IPv6 to discover other devices on the same network, determine their link-layer addresses, find routers, and maintain reachability information about paths to active neighbors.
- To implement SLAAC
- Allow a host to discover a router
- Performs interface address query
## Footnote
"Performs interface address query" refers to a similar process to ARP in IPv4, where a device queries for the link-layer address (MAC address) associated with a specific IPv6 address on the LAN
100
What does a ***Dual Stack*** device refer to?
Device that can operate IPv4 & IPv6 simultaneously
## Footnote
A host first tries to establish an IPv6 connection and switches to IPv4 if the destination doesn't support IPv6
101
What TCP/IP layer do WAN interfaces work at?
| i.e. DSL & cable modems
Link (Network interface) layer
