Chapter 6: TCP/IP Basics Flashcards
1
Q
Internet Protocol (IP)
A
Layer 3 protocol responsible for logical addressing and routing packets across networks
2
Q
Internet protocol version 4 (IPv4)
A
32 bit value written as four sets of numbers between 0 and 255 separated by a period
3
Q
What is the first version of internet protocol (IP)
A
IPv4
4
Q
Can an IP address be all 0’s and 255’s ?
A
No
5
Q
Internet control message protocol (ICMP)
A
Protocol is used to handle many low-level functions such as error or informational reporting
6
Q
Does ICMP need direct user action ?
A
No automated by software
7
Q
Which utility directly uses ICMP ?
A
Ping
8
Q
How many different fields does the IPv4 packet have ?
A
14
9
Q
Version field (IP)
A
Defines the IP address type
10
Q
Total length
A
Total size of IP packet in octets
11
Q
Time to live (TTL)
A
Prevents an IP packet from indefinitely spinning through the Internet
12
Q
What is the protocol field for IP usually ?
A
TCP or UDP
13
Q
Who decides which protocol to use ?
A
The people who develop the application
14
Q
TCP three-way handshake
A
Requires both the sending and receiving machines to ACK the other’s presence and readiness to send and receive data.
15
Q
What happens if a segment goes missing ?
A
The receiving system initiates a request for the missing segments
16
Q
What is the port number range
A
1 to 65,535
17
Q
How are port numbers used by systems ?
A
Determine what application needs the received data
18
Q
Which ports do web servers use ?
A
80(HTTP) or 443(HTTPS)
19
Q
Sequence number and acknowledgment number
A
Keep track of various pieces of data
20
Q
Flags
A
Give detailed information about the state of the connection
21
Q
Checksum
A
Check the TCP header for errors
22
Q
When does UDP work best ?
A
When you have a lot of data that doesn’t need to be perfect or when systems are close to each other
23
Q
Which protocol is faster ? TCP or UDP ?
A
UDP
24
Q
Which important networking protocols use UDP ?
A
Domain name system (DNS)
Dynamic host configuration protocol (DHCP)
25
Do UDP datagrams get chopped up ?
No they just get headers
26
What could the type field from the Ethernet header indicate ?
The size of the payload in octets or the protocol
27
How does a computer get another computers MAC address ?
Send a special query called an ARP request (address resolution protocol)
28
CMD for Windows systems current ARP cache
arp -a
29
CMD for deleting an entry in the ARP table
arp -d (ip address)
30
Are IP addresses a fixed part of the NIC ?
No
31
What are three benefits of IP addresses ?
Not a fixed part of the NIC
Group together sets of computers into logical networks
Computer communication across all of LANs that make up a WAN
32
Dotted decimal notation
Shorthand method for discussing and configuring binary IP addresses using a 10 base numbering system
33
Must every IP address be unique ?
Yes
34
Which CMD to display the IP and MAC addresses ?
ipconfig /all
35
What is the CMD for macOS to display IP and MAC addresses ?
ifconfig
36
What three things must an IP numbering system do to support WANs and LANs ?
Have a network ID, interconnect LANs using routers, and use a subnet mask
37
Network ID
Numbers used in IP addresses to identify the network portion
38
Host ID
Portion of an IP address that defines a specific machine in a subnet
39
Can an individual system have a host ID of 0 ?
No they are reserved for Network IDs
40
How does a TCP/IP LAN connect to another ?
Router connections
41
Do routers need an IP address on every LAN it interconnects?
Yes
42
What is the router's interface on the LAN and the router itself also called ?
Default gateway
43
What do routers use to determine network traffic?
Network IDs
44
Routing table
Instructions that tell the router what to do with the incoming packets and where to send them
45
Could you change your Network ID?
Only if there is no other LAN on the WAN that shares the same network ID
46
What does the host ID 255 indicate?
A broadcast address
47
Where does a computer send the packet when it's sending to a faraway network ?
Default gateway
48
Subnet mask
Value used in TCP/IP settings to divide the IP address of a host into its component parts: network ID and host ID
49
Which part of the subnet mask aligns with the network ID ?
The ones
50
What does a computer compare before sending out any data ?
Network IDs
51
What if the network ID does not match the destinations network ID ?
It's a long distance, outside the local LAN
52
If the IP address is not local, why does a computer send out an ARP broadcast ?
To learn the MAC address for the default gateway
53
CIDR notation
A character followed by a number equal to the number of ones in the subnet mask
54
What does the example tell you ? Ex: 192.168.12.3/24. What's the subnet mask ?
Tells the IP address and the subnet mask
255.255.255.0
55
Do all computers on the same network have the same subnet mask and netwrok ID ?
By definition
56
Internet assigned numbers authority (IANA)
Formed to track and disperse IP addresses to those who need them
57
What does IANA oversee ?
Five regional internet registries (RIR)
58
What is the name of the American RIR ?
American Registry for Internet Numbers (ARIN)
59
Network blocks
Ranges of IP addresses that are assigned to organizations and end users by IANA
60
Clasful
Describes the traditional class blocks
61
Internet corporation for assigned names and numbers (ICANN)
Manages IANA, but more focused on the policy
62
Class A, Class B, Class C
First octect defines network ID, two octets define network ID, three octets define network ID
63
Multicast class blocks
Used for one-to-many communication
64
Broadcast
Every computer on the LAN hears the message
65
Anycast
Multiple computers share a single address and routers' direct message to closest computer
66
Multicast
A single computer sends a message to a group of interested computers
67
What do routers use to talk to each other ?
Multicast
68
Classless inter-domain routing (CIDR)
New method of generating blocks of IP addresses
69
Subnetting
Taking a single class of IP addresses and chopping it up into multiple smaller groups (subnets)
70
What does subnetting provide ?
Separate a network for security and for bandwidth control
71
What two things are important to remember about subnetting ?
Start with the given subnet and move it to the right until you have the subnets you need
Always convert to binary
72
What's the formula for calculating the number of hosts ?
2^x-2
x=number of zeros in the subnet mask
73
Formula for determining how many subnets are created
2^y
y=number of bits added to the subnet mask
74
Two goals for subnetting ?
Efficiency and making multiple networks from a single network ID
75
What is CIDR also referred to ?
Classless address
76
Variable-length subnet masking (VLSM)
Taking a single network ID and handing out custom subnets
77
Static addressing
Typing in all IP information manually (IP address, subnet mask, default gateway)
78
Dynamic Host Configuration Protocol (DHCP)
Automatically assigns IP information when connecting to network
79
What happens to static addressing if a system reboots ?
The IP address is lost and is not permanent
80
What's static addressing used for ?
More-critical systems
81
Why is static addressing tedious ?
Hard to make changes to the network
82
What does a network using DHCP consist of ?
DHCP client and DHCP server
83
Where are DHCP servers ?
Built into the router or on a rack for enterprise use
84
What is in the DHCP Offer message ?
IP information (IP address, default gateway, subnet mask, and more)
85
What happens during a DHCP ACK ?
Clients MAC address and IP information are listed in a database
86
DHCP request
Message from the client to the server accepting the offer from this DHCP server only
87
Another name for the DHCP four-way handshake ?
DORA
88
Are DHCP clients preconfigured by default ?
Yes
89
What three things does a DHCP server require ?
Pool of legitimate IP addresses, know the default gateway IP address, know the subnet mask
90
DHCP scope
Range of IP addresses
91
DHCP relay
Enables routers to accept DHCP broadcasts from clients and use UDP forwarding to send it directly to the server
92
Should there be multiple DHCP server on a small LAN ?
No just one
93
What does the DHCP relay capable device need to work ?
The real IP address of the DHCP server
94
IP exclusion range
Reduce the size of the pool of the assignable addresses to avoid that range
95
MAC reservations
Give the same IP information to the same host each time
96
What does a zero configuration networking or automatic private IP addressing mean ?
No response from a DHCP Discover message
97
Windows command to reestablish the lease ?
Ipconfig /renew
98
Windows command to release lease
Ipconfig /release
99
What can't APIPA do ?
Issue a default gateway
100
DHCP Failover
Only two DHCP servers work together to provide DHCP to the network (primary and secondary DHCP servers)
101
Rogue DHCP servers
Passing out incorrect IP information to clients
102
Private IP addresses ranges
10.0.0.0-10.255.255.255
172.16.0.0-172.16.255.255
192.168.0.0-192.168.255.255
103
Loopback address
Sending packets to itself
104
Can private IP addresses ever be used on the internet ?
Never
105
Port # DHCP server & client
67 & 68
