Network Basics Flashcards
1
Q
List each layer (7 to 1) of the OSI Seven-Layer Model.
A
L7 Application
L6 Presentation
L5 Session
L4 Transport
L3 Network
L2 Data Link
L1 Physical
Remember the mnemonic “All People Seem To Need Data Processing.”
2
Q
In Windows, type ______ from a command prompt to display the MAC address.
A
ipconfig /all
3
Q
In macOS, type ______ from a terminal to display the MAC address.
A
ifconfig
4
Q
In Linux, type ______ from a terminal to display the MAC address.
A
ip a
5
Q
What is the PDU for Layer 2, the Data Link layer?
A
Frame (Ethernet)
6
Q
What is the max size of an Ethernet frame’s Data field?
A
1500 bytes
7
Q
What is the Layer 2 broadcast address?
A
FF-FF-FF-FF-FF-FF
8
Q
What are the two sublayers of the Data Link layer?
A
Logical Link Control (LLC)
Media Access Control (MAC)
9
Q
What is the PDU for Layer 3, the Network layer?
A
Packet
10
Q
Define: MAC or Media Access Control Address (aka. a physical address)
A
A 48-bit (6-byte) unique identifier that is burned onto a ROM chip in every NIC. It is in hexadecimal notation (12 hex digits).
11
Q
What is an IPv4 address?
A
An IPv4 address is 32-bits (4 bytes) long. It uses dotted decimal notation based on four 8-bit numbers. Each byte is separated by a decimal (192.168.4.232).
12
Q
What are the PDUs for the Transport Layer?
A
Segments (TCP) and Datagrams (UDP)
13
Q
What logical addressing is used in the Transport Layer?
A
Port addressing
14
Q
What is a port?
A
A port - a number between 1 and 65,535 - is a logical value assigned to specific applications or services.
15
Q
What type of connector does coaxial cable use?
A
F-type connector
16
Q
What two types of coaxial cables are used and what are their Radio Guide Ohms rating?
A
RG-6 at 75 Ohms
RG-59 at 75 Ohms
(RG-6 is the predominant cable used to connect modems to an ISP)
17
Q
Cat 5 frequency and bandwidth
A
100 MHz
100 Mbps
18
Q
Cat 5e frequency and bandwidth
A
100 MHz
1 Gbps
19
Q
Cat 6 frequency and bandwidth
A
250 MHz
10 Gbps
20
Q
Cat 6a frequency and bandwidth
A
500 MHz
10 Gbps
21
Q
Cat 7 frequency and bandwidth
A
600 MHz
10+ Gbps
22
Q
Cat 8 frequency and bandwidth
A
2000 MHz
25-40 Gbps
23
Q
What connector does twisted pair use?
A
Technically 8 position 8 contact (8P8C) connectors but commonly called RJ-45 connectors (Network + uses the latter)
24
Q
What are the two types of fiber-optic cables?
A
Multimode Fiber (MMF)
Single-mode Fiber (SMF)
25
What four connectors are used with fiber-optic cables?
ST (Single Tube)
SC (Single Cube)
LC (Little Cubes)
MT-RJ (Mechanical Transfer-Register Jack; slightly resembles RJ-45)
26
Plenum-rated cable fire rating
Safe for the ceiling plenum space and a better choice for vertical runs between floors over riser-rated cables. If it goes in the ceiling or wall, make it plenum.
27
What pins on an RJ-45 connector are used by 10BASE-T devices?
Pins 1 and 2 send data, and pins 3 and 6 receive data.
28
What is the wire termination order for 568A twisted pair Ethernet cabling?
From left to right:
1. Green/White
2. Green
3. Orange/White
4. Blue
5. Blue/White
6. Orange
7. Brown/White
8. Brown
Remember "GO"
29
What is the wire termination order for 568B twisted pair Ethernet cabling?
From left to right:
1. Orange/White
2. Orange
3. Green/White
4. Blue
5. Blue/White
6. Green
7. Brown/White
8. Brown
30
10BASE-T Summary:
Speed
Distance
Node Limit
Cable Type
Speed: 10 Mbps
Distance: 100 m
Node Limit: No more than 1024 nodes per hub
Cable Type: Cat 3 or better UTP
31
What does Spanning Tree Protocol (STP) do, and what special type of frame does it use for communication between switches?
STP eliminates the problem of accidental switching loops by electing one switch as the root bridge. Bridge protocol data units (BPDUs) are the frames used to communicate between switches.
32
What protocol replaced STP?
Rapid Spanning Tree Protocol (RSTP)
33
100BASE-T
Speed
Distance
Node Limit
Cable Type
Speed: 100 Mbps
Distance: 100 m
Node Limit: 1024 nodes per hub/switch
Cable Type: Cat 5 or better UTP or STP
34
100BASE-FX
Speed
Distance
Node Limit
Cable Type
Speed: 100 Mbps
Distance: 2 km
Node Limit: 1024 nodes per hub/switch
Cable Type: Multimode fiber-optic (generally OM1) with ST or SC connectors
35
100BASE-SX
Speed
Distance
Cable Type
Speed: 100 Mbps
Distance: Short
Cable Type: Multimode fiber-optic OM1 or OM2 with ST, SC, or LC connectors
36
What is the IEEE 802.3ab standard called?
1000BASE-T (Gigabit Ethernet)
37
What is the IEEE 802.3z standard called?
1000BASE-X (Gigabit Fiber-Optic)
38
1000BASE-T
Speed
Length
Cable Type
Cable Details
Speed: 1 Gbps
Length: 100 m
Cable Type: Cat 5e/6 UTP
Cable Details: Four-pair/ full-duplex
39
1000BASE-SX
Speed
Length
Cable Type
Speed: 1 Gbps
Length: 220-500 m
Cable Type: Multimode fiber, OM2 or better
40
1000BASE-LX
Speed
Length
Cable Type
Speed: 1 Gbps
Length: 5 km
Cable Type: Single-mode fiber OS1 or OS2
41
10GBASE-SR/SW
Speed
Length
Cabling
Speed: 10 Gbps
Length: 33-400 m
Cabling: Multimode fiber (OM3 or better)
42
10GBASE-LR/LW
Speed
Length
Cabling
Speed: 10 Gbps
Length: 10 km
Cabling: Single-mode fiber (OS2 required to reach the full distance)
43
10GBASE-ER/EW
Speed
Length
Cabling
Speed: 10 Gbps
Length: 40 km
Cabling: Single-mode fiber
44
10GBASE-T
Speed
Length
Cabling
Cable Details
Speed: 10 Gbps
Length: 55/100 m
Cabling: Cat 6/6a UTP
Cable Details: Four-pair/ full-duplex
45
40GBASE-T
Speed
Distance
Cabling
Speed: 40 Gbps
Distance: 30 m
Cabling: Cat 8 UTP
46
What is the official ANSI/TIA naming convention for patch panels?
ANSI/TIA-606-C
47
What is the TIA/EIA 568 specification for UTP horizontal cabling length?
90 m, reserving 10 m for patch cables.
48
What is the TCP three-way handshake?
SYN
SYN-ACK
ACK
49
What does Address Resolution Protocol (ARP) do?
It resolves an IP address to an Ethernet MAC address.
50
What command do you type in Window's Command Prompt to view the system's current ARP cache?
arp -a
51
What command do you type in Window's Command Prompt to delete one of the entries in the ARP table?
arp -d [ip address from the cache table]
52
What command do you type in the Window's Command Prompt to display the IP and MAC addresses?
ipconfig /all
53
What command do you type in the macOS terminal to display the IP and MAC addresses?
ifconfig
54
What command do you type in the Linux terminal to display the IP and MAC addresses?
ip address
(ifconfig is the older command)
55
Class A IP block:
First Decimal Value
First Binary Octet
Addresses
Subnet Mask
First Decimal Value: 1-126
First Binary Octet: 0xxxxxxx
Addresses: 1.0.0.0-126.255.255.255
Subnet Mask: 255.0.0.0
56
Class B IP block:
First Decimal Value
First Binary Octet
Addresses
Subnet Mask
First Decimal Value: 128-191
First Binary Octet: 10xxxxxx
Addresses: 128.0.0.0-191.255.255.255
Subnet Mask: 255.255.0.0
57
Class C IP block:
First Decimal Value
First Binary Octet
Addresses
Subnet Mask
First Decimal Value: 192-223
First Binary Octet: 110xxxxx
Addresses: 192.0.0.0-223.255.255.255
Subnet Mask: 255.255.255.0
58
Class D IP block (Multicast):
First Decimal Value
First Binary Octet
Addresses
First Decimal Value: 224-239
First Binary Octet: 1110xxxx
Addresses: 224.0.0.0-239.255.255.255
59
Class E IP block (Experimental):
First Decimal Value
First Binary Octet
Addresses
First Decimal Value: 240-255
First Binary Octet: 1111xxxx
Addresses: 240.0.0.0-255.255.255.255
60
What is the formula to determine how many hosts a network can have?
2^x - 2, where x represents the number of zeroes in the subnet mask.
You subtract two for the network ID (host ID all zeroes) and broadcast address (host ID all 255s).
61
Define: Anycast packet
Where multiple computers share a single address and routers direct messages to the closest computer.
62
Define: Broadcast packet
Where every computer on the LAN hears the message.
63
Define: Multicast packet
Where a single computer sends a message to a group of interested computers. Routers use multicast to talk to each other.
64
What is subnetting?
Taking a single class of IP addresses and chopping it up into multiple smaller groups called subnets. You take an existing /8, /16, or /24 subnet and extend the subnet mask by replacing zeroes with ones.
65
List the steps to create a Classless Inter-Domain Routing (CIDR) subnet.
1. Write the existing subnet mask out in binary and place a vertical line at the end of the ones.
2. Extend the network ID by replacing one or more zeroes with a one until you have the number of subnets that you need. Place a second vertical line at the end of your new one(s).
3. Convert your new /(# of 1s) subnet mask into dotted decimal.
66
What is the formula for determining how many subnets you create in subnetting?
2^y, where y is the number of bits (ones) you add to the subnet mask.
2^1 = 2
2^2 = 4
2^3 = 8
67
What are the steps to create the new networks IDs for the subnets created in subnetting?
1. Convert the original network ID into binary.
2. Add the network ID extensions to the end for each of the subnets you created.
3. Convert the new network IDs for your subnets into dotted decimal.
68
What is the DHCP four-way Handshake?
Discover
Offer
Request
Acknowledgment
(DORA)
69
What port number do DHCP servers use?
port 67
70
What port number do DHCP clients use?
port 68
71
What is the network ID for APIPA?
169.254.0.0/16
The DHCP client only generates the last two octets of an APIPA address.
72
What command do you type in the Window's command prompt to reestablish the DHCP lease manually?
ipconfig /renew
73
What command do you type in the Window's command prompt to force a client to release its DHCP lease?
ipconfig /release
74
What command do you type into macOS to force a client to release a DHCP lease?
sudo ifconfig eth0 down
*Also old command for Linux
75
What command do you type in macOS to renew a DHCP lease manually?
sudo ifconfig eth0 up
*Also old command for Linux
76
What command do you type in Linux to force a client to release a DHCP lease?
sudo dhclient -r
77
What command do you type in Linux to renew a DHCP lease manually?
sudo dhclient
78
What subnet is reserved for loopback addresses?
127.0.0.0/8
127.0.0.1 is the traditional loopback address used.
79
What are the private IP address ranges?
10.0.0.0 - 10.255.255.255 (1 Class A network block)
172.16.0.0 - 172.31.255.255 (16 Class B network blocks)
192.168.0.0 - 192.168.255.255 (256 Class C network blocks)
80
What command do you type in a terminal on Linux to view a computer's routing table?
ip route
81
What command do you type in both macOS and Windows to view a computer's routing table?
netstat -r
82
What does Network Address Translation (NAT) do?
NAT replaces the source IP address of a computer with the source IP address from the outside router interface on outgoing packets. NAT is performed by NAT-capable routers.
Routers running some form of NAT hide the IP addresses of computers on the LAN but still enable Internet access.
83
What does Port Address Translation (PAT) do?
The router running PAT records the source and destination IP addresses and port numbers for the TCP segment or UDP datagram and translates the private IP address for a public IP address and the source port number for a unique port number.
84
What are the three distinct groups of dynamic routing protocols?
Distance Vector
Link State
Hybrid
85
What are the two distance vector routing protocols?
Routing Information Protocol: RIPv1 and RIPv2
86
What is the one EGP that the Internet uses for AS-to-AS communication?
Border Gateway Protocol (BGP)
Current version BGP-4
87
What are the two Link State dynamic routing protocols?
Open Shortest Path First (OSPF)
Intermediate System to Intermediate System (IS-IS)
88
After OSPF-capable routers send out Hello packets and establish a neighborship with adjacent routers, what type of packets do they send to exchange information about routers and networks?
Link State Advertisement (LSA) packets
89
What type of dynamic routing protocol is Enhanced Interior Gateway Routing Protocol (EIGRP) and who developed it?
Hybrid
It has aspects of both distance vector and link state protocols.
Cisco developed it.
90
What are the four Interior Gateway Protocols (IGPs)?
RIP
OSPF
IS-IS
EIGRP
91
What do you call (three common names) the serial cable used to connect to and communicate with a router?
Console cable
Rollover cable
Yost cable
92
What are the two terminal emulation protocols that allow you to connect to routers?
Telnet (older, not secure)
Secure Shell (SSH)
These allow you to use the network instead of a serial cable.
93
What command do you type in the Windows command prompt to record the route between any two hosts and the information of every router between them?
tracert
94
What command do you type in a terminal for macOS/UNIX/Linux to record the route between any two hosts and the information of every router between them?
traceroute
95
What Windows command line tool pings each node on a route and computes the performance over a set time and then shows you the summary after it has finished?
pathping
96
What Linux tool is dynamic and continually updates the route you have selected?
My traceroute (mtr)
97
What are five important protocols that use User Datagram Protocol (UDP) in their sessions?
DNS (Domain Name System)
DHCP (Dynamic Host Configuration Protocol)
NTP (Network Time Protocol)
SNTP (Simple Network Time Protocol)
TFTP (Trivail File Transfer Protocol)
98
What does Domain Name System (DNS) protocol do?
It enables the use of domain names associated with IP addresses for devices connected to IP networks, such as the Internet and private intranets.
99
What do Network Time Protocol (NTP) and Simple Network Time Protocol (SNTP) do?
They use UDP to synchronize the clocks of devices on a network.
If a device requires NTP/SNTP, then enter the IP address for an NTP/SNTP server onto that device.
100
What does Trivial File Transfer Protocol (TFTP) do?
It enables you to transfer files from one machine to another using UDP, but lacks data protection.
101
What does Internet Control Message Protocol (ICMP) do?
It works at Layer 3 to handle low-level tasks such as the ping utility sending a single ICMP message called an "echo request" to an IP address you specify.
102
What does Internet Group Management Protocol (IGMP) do?
It enables routers to communicate with hosts and switches to determine a "group" membership for IP multicast addresses (Class D range).
103
Define: Well Known Ports
Number Range: _______
Ports reserved for specific TCP/IP applications.
0 - 1,023
104
Define: Registered Ports
Number Range: _________
Ports that less common TCP/IP applications can register for with IANA.
Anyone can use these port numbers for their servers or for ephemeral numbers on clients.
1,024 - 49,151
105
Define: Dynamic, Ephemeral, or Private Ports
Number Range: ________
Ports that are pseudo-randomly generated for a client computer's application use.
49,152 - 65,535
106
What does the netstat command utility do on Windows and macOS?
Lists the endpoints of your computer's communication partners.
107
What does the netstat -n switch do?
It instructs netstat to show port numbers and IP addresses.
netstat -n
108
What does the netstat -a switch do?
It tells netstat to show all used ports, including "listening" ports not engaged in active communications.
netstat -a
109
What does the netstat -o switch do?
It tells netstat to show the process ID.
netstat -o
110
What does the netstat -b switch do?
It tells netstat to give the name of the running program behind the PID (process ID).
netstat -anob
111
What does the Telnet protocol do?
It enables command-line remote access to another computer. The sent data is not encrypted.
112
What does the Secure Shell (SSH) protocol do?
It enables remote access via terminal emulation to a remote computer. Both the login and data transmittal are encrypted.
113
What does the Simple Mail Transfer Protocol (SMTP) do?
It sends e-mail from clients and between e-mail servers.
114
What does Post Office Protocol version 3 (POP3) do?
It retrieves e-mail from e-mail servers.
115
What does Internet Message Access Protocol version 4 (IMAP4) do?
It retrieves e-mail from an e-mail server and enables synchronization of mail among many devices.
It also supports folders that you can place on the IMAP4 server to organize your e-mail.
116
What does the File Transfer Protocol (FTP) do?
It transfers files on the Internet, but does not use encryption by default and sends login information in cleartext.
117
What is Hypertext Transfer Protocol (HTTP)?
It is the underlying protocol used by Web servers.
HTTP defines the commands that browsers (and other software) use to ask Web servers for things and how the server will format what it sends back to the browser.
118
What does Hypertext Transfer Protocol Secure (HTTPS) do?
It enables secure connections between clients and servers by using Transport Layer Security (TLS).
119
FTP
Port #
TCP Ports: 20/21 (active), 21 (passive)
120
SSH
Port #
TCP Port: 22
121
Telnet
Port #
TCP Port: 23
122
SMTP
Port #
TCP Port: 25
123
DNS
Port #
UDP Port: 53
124
DHCP
Port #
UDP Port: 67 (server), 68 (client)
125
TFTP
Port #
UDP Port: 69
126
HTTP
Port #
TCP Port: 80
127
POP3
Port #
TCP Port: 110
128
NTP/SNTP
Port #
UDP Port: 123
129
IMAP4
Port #
TCP Port: 143
130
HTTPS
Port #
TCP Port: 443
131
Define: Server Message Block (SMB)
A Layer 7 protocol that supports sharing folders and files.
132
SMB
Port #
TCP port: 445
133
What do DNS name servers do?
They hold the actual name and IP DNS records in a database called a zone.
134
What do Top-Level Domain (TLD) servers do?
They handle the top-level domain (TLD) names, such as .com, .org, .net, .edu, .gov, .mil, .int, and delegate to domain-specific name servers (authoritative name servers).
135
In a Windows command prompt, what do you type to see a host's DNS cache?
ipconfig /displaydns
136
Define: DNS record type - SOA (Start Of Authority)
Every zone requires an SOA record that defines the primary name server in charge of the zone.
137
Define: DNS record type - NS (Name Server)
An NS record points to the server that holds the records (zone) for a part of the DNS tree.
NS records enable the name servers to know where to point the resolvers to find the authoritative name servers for a specific domain below them in the DNS hierarchy.
138
Define: DNS record type - A (Address)
An A record holds the IPv4 address for a host.
139
Define: DNS record type - AAAA (Quad A)
An AAAA record holds the IPv6 address for a host.
The four A letters signify that IPv6 addresses are four times longer than IPv4 addresses (128 bits vs. 32 bits).
140
Define: DNS record type - CNAME (Canonical Name)
A CNAME record holds the FQDN for an alias that is used.
141
Define: DNS record type - PTR (Pointer)
A PTR record reverses the functions of A or AAAA records, and are found only in reverse lookup zones. They use an IP address for their names and hold the FQDN of a host at that address.
142
Define: DNS record type - MX (Mail Exchange)
MX records hold the FQDN of the server that handles mail for the domain.
SMTP servers use MX records exclusively to determine where to send mail.
143
Define: DNS record type - SRV (Service)
A SRV record is a generic DNS record that supports any type of server by specifying the location of services.
144
Define: DNS record type - TXT (Text)
A TXT record is a freeform type of record that can be used for anything.
One use is to enable domains to verify that e-mail being received by a third-party e-mail server is sent by a legitimate server within the domain to help secure against e-mail spoofing.
145
What does the Dynamic DNS (DDNS) protocol do?
It enables DNS servers to get automatic updates of the IP addresses for the computers in their forward lookup zones by communications with the local DHCP server.
146
What do you type in a Windows command prompt to flush the local system's DNS cache?
ipconfig /flushdns
147
What do you type in a Windows command prompt to enable DNS server queries?
nslookup [IP address or FQDN] [optional DNS server IP address]
148
Any encryption that uses the same key for both encryption and decryption is called:
symmetric-key encryption
149
Any encryption that uses different keys for encryption and decryption is called:
asymmetric-key encryption
150
Symmetric-key algorithms are either ____ ciphers or ____ ciphers.
block
stream
151
Public-key cryptography, the primary asymmetric implementation, generates a key pair. What are these keys called?
private key
public key
152
How does asymmetric-key encryption solve the weakness of symmetric-key encryption?
The public key of the receiver is used to encrypt the symmetric-key before it is sent, and the receiver uses their private key to decrypt it.
153
What are the three asymmetric algorithms used today?
RSA (Rivest, Shamir, Adleman)
DSA (Digital Signature Algorithm)
ECDSA (Elliptic Curve DSA)
154
What is the primary family of cryptographic functions and which two are currently recommended?
SHA (Secure Hash Algorithm)
SHA-2 (six variants)
SHA-3 (six variants)
155
The system for creating and distributing digital certificates issued by trusted third party certificate authorities (CA) such as DigiCert, GoDaddy, or Sectigo is called:
PKI (Public-Key Infrastructure)
156
What does AAA stand for in network security?
Authentication
Authorization
Accounting
157
____ enables two devices to connect, authenticate with a username and password, and negotiate the network protocol the two devices will use.
PPP or Point-to-Point Protocol
158
PPP switched from PAP to ____ for a secure authentication routine using hashes.
CHAP or Challenge Handshake Authentication Protocol
159
____ servers provides AAA for remote users accessing a network using point-to-point connections.
RADIUS or Remote Authentication Dial-In User Service
160
The ____ protocol supports AAA in a network with many routers and switches that need administration. It is similar to RADIUS in function.
TACACS+ or Terminal Access Controller Access Control System Plus
161
TACACS+
Port #
TCP port 49
162
The authentication protocol ____ is used for TCP/IP networks with many clients all connected to a single authenticating server. Microsoft Windows domains rely on it for authentication.
Kerberos
163
Kerberos
Port #
UDP or TCP port 88
164
What protocol offers secure file transfers, resumption of interrupted file transfers, deletion of files on the server, and more?
SFTP or SSH File Transfer Protocol
165
SFTP
Port #
TCP port 22
166
What protocol queries the state of network devices and reports whatever device-specific information the devices provide?
SNMP or Simple Network Management Protocol
SNMPv3 is the standard version used today.
167
SNMP
Port #s
UDP ports 161 and 162
168
What protocol do programs use to query and change a database used by the network (ie. Active Directory)? Domain controllers will use it automatically in the background to keep your databases in good order.
LDAP or Lightweight Directory Access Protocol
169
LDAP
Port #s
TCP port 389
UDP port 389
