2.1 - 2.2 Networking Protocols and Hardware Flashcards
What are the five parts of (IP) Internet Protocol?
Ethernet header (client)
IP (internet protocol)
TCP (transmission control protocol)
HTTP data
Ethernet trailer (server)
What’s the difference between TCP and UDP?
TCP (transmission control protocol) is a connection-based protocol. It’s reliable, so it can reorder data, conduct retransmissions, and manage data limits.
UDP (user datagram protocol) is a connectionless protocol. It’s unreliable, meaning it has no error recovery or receipt of data sending. No flow control
What is multiplexing?
Uses both TCP and UDP to transmit data for many different applications at the same time
DHCP and TFTP are examples of: TCP or UDP? What do they stand for?
UDP
Dynamic Host Configuration Protocol
Trivial file transfer protocol
Protocols like HTTP and HTTPS are examples of: UDP or TCP?
TCP. They require a return receipt
What is a port number?
It’s written on the outside of a packet to ensure that the contents get to the right application
What are the parts of an IPv4 packet?
Server IP address, protocol, server application port number
Client IP address, protocol, client port number
What are non-ephemeral ports?
Permanent port numbers usually on a server or service. Usually go from 0 to 1023. Ex, port 80 = HTTP, port 443 = HTTPS
What are ephemeral ports?
Temporary port numbers that are determined in real-time by the client. Usually between 1024 and 65,535
Why is it important that port numbers should be well known numbers?
Port numbers are for communication, not security. This prevents us from having another system to create / decode port numbers, which would complicate communication
What is TCP port 20 / 21?
20 = data transfer port in FTP (file transfer protocol)
Authenticates with a username and a password
Can add / delete / transfer files
What is TCP port 21?
21 = default port used for control channel in FTP (file transfer protocol)
What is TCP port 22?
SSH (secure shell)
Encrypted communication link
Connects you to a remote device through command line
What is TCP port 23 and when would you use it?
Telnet (telecommunication network protocol)
Lets us connect to a device remotely
This information is not encrypted, so be wary of using Telnet on production systems
What is TCP port 25 and when would you use it?
SMTP (simple mail transfer protocol)
Used to send email (not usually to receive)
Server to server email transfer
Device to server email transfer
What is UDP port 53 and when would you use it?
DNS (domain name system)
Converts names to IP addresses
What is UDP port 67?
Used by DHCP servers to communicate with clients on a network
Uses a leasing system
Able to reserve static IP addresses (admins, etc.)
What is UDP port 68?
Used by DHCP servers to respond to messages
What is TCP port 80 / 443 and when are they used?
Port 80 = HTTP (hypertext transfer protocol)
Port 443 = HTTPS (hypertext transfer protocol secure)
Which one you’re using depends on whether you’re connecting to the web with encryption (HTTPS) or in-the-clear (HTTP)
What is TCP port 110?
POP3 (post office protocol version 3)
Basic email authentication and transfers for one inbox
What is TCP port 143?
IMAP (internet message access protocol v4)
Includes management of email inbox from multiple clients
What is SMB?
Server message block, a protocol used by Microsoft Windows
Used for file sharing and printer sharing
Also called CIFS (common internet file system)
Uses NetBIOS over TCP/IP (network basic input/output system)
What is UDP port 137?
NetBIOS name service (nbname)
Port used by SMB
Allows users to access shared resources such as files and printers over a network
What is TCP port 139?
NetBIOS session service (nbsession)
Port used by SMB to facilitate communication between devices in Windows OS
What is TCP port 445?
Port used by SMB in earlier versions of Windows OS. Allows direct connection on the internal network without using NetBIOS
What is SNMP?
Simple network management protocol
Allows network management device to query devices for performance details
V1 = the original, in-the-clear
V2 = bulk transfers, in-the-clear
V3 = modern secure standard, authentication, encryption
What is UDP port 161?
Default port used by SNMP for managers to communicate with agents. Used to listen for queries
What is UDP port 162?
Used by SNMP for unsolicited notifications or “traps”
What is TCP port 389?
LDAP (lightweight directory access protocol)
Stores and retrieves information in a network directory
Commonly used in Microsoft Active Directory
What is TCP port 3389?
RDP (remote desktop protocol)
Lets you share a desktop from a remote location
Available in many versions of Windows
Available in clients for other OS
What does a router do?
Routes traffic between IP subnets
Routers inside of switches are sometimes called level 3 switches (referring to the OSI model)
How is a switch different from a router?
Uses the MAC address to direct traffic instead of IP
Very fast throughput because the circuits are application-specific integrated (ASIC)
The following 2 are features of what hardware?
-They’re comprised of many ports and features, may provide Power over Ethernet (PoE)
-Can be multilayered by including router functionality (level 3)
Switch
What’s one pro and one con to unmanaged switches?
Pro = low cost, plug and play with very few configuration options
Con = no management protocols such as SNMP
What kind of switch would you purchase for an office?
Managed switch. Provides things like:
VLAN support (interconnects with other switches through 802.1Q
Traffic prioritization (VoIP > other traffic)
Redundancy support (STP, spanning tree protocol)
Port mirroring
External management (like SNMP)
How is an access point different from a router?
A router contains an access point. An access point does not route anything, it’s a bridge that extends the wired network onto the wireless network.
Uses MAC address to make forwarding decisions
What does cable infrastructure look like?
Wires connect a bunch of workstations to a patch panel. We extend the connection through RJ45 ports to the switch. Patch panel lets you move to different switches for new hires / desk switches
What is a benefit to using patch panels?
They use existing cables and don’t require any special tools, so they can be easily changed
What is a firewall’s main function?
To filter traffic by port number (OSI layer 4) or by application (OSI layer 7). Can encrypt traffic in and out of network and also proxy traffic.
Most firewalls can also be layer 3 devices if they are built into routers
What is PoE?
Power over Ethernet. It transfers data and also powers a device in one connection. Usually used in cameras and access points
What are two kinds of PoE?
Endspans (built-in-power)
Midspans (in-line power injector)
Both of these are accessed through the switch
What are the different PoE standards?
2003 => PoE IEEE 802.3af.
The original, now part of the 802.3 standard. Supports 15.4 watts of DC power, 350 mA max current
2009 => PoE+ IEE 802.3at.
Now also part of 802.3 standard. Supports 25.5 watts of DC power, 600 mA max current
2018 => PoE++ IEEE 802.3bt.
Type 3 PoE++ provides 51 W of power and 600 mA max current.
Type 4 provides 71.3 W of power and 960 mA max current.
Designed to power 10GB ethernet
What did we use before switches?
Hubs or multi-port repeaters. Not very efficient because everything is half-duplex. Becomes less efficient as network traffic increases
What is a device that runs both a TV and internet connection?
Cable modem. Allows you to connect via broadband. The standard is called DOCSIS (data over cable service interface specification). Supports speeds up to 1GB per second
If you’re connecting to the internet with your phone company, what kind of modem are you using?
DSL or ADSL (asymmetric digital subscriber line). It’s asymmetric because download speeds are much faster than upload speeds. Speeds are limited by proximity to central office (CO)
What kind of device are you using to connect to the internet using fiber?
ONT, optical network terminal. Converts fiber to copper ethernet wires. Uses a demarcation point (demarc) to differentiate your network from the ISP’s network
What’s the name of a card used to connect your device with a copper ethernet connection?
NIC, network interface card. The fundamental network device, every device on the network has a NIC.
Can also function to connect with Ethernet, WAN, WWAN
What is SDN?
Software defined networking. Separates function of switch into individual pieces that are converted to software / the cloud
