Networking CompTIA 6 Quiz review

Transport Layer

OSI Layer 4 responsible for the transparent transfer of data and end-to-end error recovery

Port

A 16-bit identifier (0-65,535) used to direct traffic to specific applications or services

Socket

The combination of an IP address and a port number (e.g., 10.1.0.1:80)

Multiplexing

The process of sending multiple application data streams over a single network connection using ports

Connection-oriented

A type of communication that requires a formal handshake and guarantees delivery (TCP)

Connectionless

A "best-effort" communication type that prioritizes speed over reliability (UDP)

TCP Segment

The Protocol Data Unit (PDU) at the Transport Layer for TCP

Flow Control

A TCP mechanism using the Window field to prevent the sender from overwhelming the receiver

Ephemeral Port

A temporary port (49,152-65,535) assigned to client applications for the duration of a session

DHCP Server

A device that automates the assignment of IP addresses, subnet masks, and gateways

APIPA purpose

A link-local address (169.254.x.x) assigned automatically when a DHCP server is unreachable

SLAAC purpose

An IPv6 method where hosts configure their own addresses using router advertisements

DHCP Reservation

A static mapping of a MAC address to a specific IP address within a DHCP pool

DHCP Scope

The range of IP addresses available for a DHCP server to lease to a specific subnet

Exclusion

A specific IP or range within a scope that the DHCP server is blocked from assigning

TCP

Transmission Control Protocol

UDP

User Datagram Protocol

DHCP

Dynamic Host Configuration Protocol

DORA

Discover, Offer, Request, Acknowledge (The 4-step DHCP process)

IANA

Internet Assigned Numbers Authority

APIPA

Automatic Private IP Addressing

SLAAC

Stateless Address Autoconfiguration

NDP

Neighbor Discovery Protocol

RA / RS

Router Advertisement / Router Solicitation

NA / NS

Neighbor Advertisement / Neighbor Solicitation

MSS

Maximum Segment Size

PID

Process Identifier

TCP Three-Way Handshake

1. SYN (Client) -> 2. SYN/ACK (Server) -> 3. ACK (Client)

DHCP DORA Process

1. Discover (Client) -> 2. Offer (Server) -> 3. Request (Client) -> 4. Acknowledgment (Server)

TCP Connection Teardown

1. FIN -> 2. ACK -> 3. FIN -> 4. ACK

DHCP Lease Renewal (T1)

Happens at 50% of the lease time

client requests renewal from the original server

DHCP Lease Rebinding (T2)

Happens at 87.5% of the lease time

client broadcasts to find any available server

IPv6 SLAAC Process

1. Generate Link-Local -> 2. Send Router Solicitation -> 3. Receive Router Advertisement -> 4. Configure Prefix

FTP (Data/Control)

TCP 20/21

SSH / SFTP

TCP 22

Telnet

TCP 23

SMTP

TCP 25

DNS

TCP/UDP 53

DHCP Server / Client

UDP 67 / UDP 68

HTTP

TCP 80

POP3

TCP 110

NTP

UDP 123

IMAP

TCP 143

SNMP

UDP 161

HTTPS

TCP 443

DHCPv6 Client / Server

UDP 546 / UDP 547

RDP

TCP 3389

netstat -a

Displays all active connections and listening ports

netstat -n

Displays addresses and ports in numerical format (skips DNS resolution)

netstat -o (Windows)

Displays the PID (Process ID) for each connection

netstat -p (Linux)

Displays the PID and the name of the process owning the socket

netstat -r

Displays the local routing table

netstat -s

Displays statistics per protocol (TCP, UDP, IP)

netstat -i (Linux)

Displays network interface statistics (errors, drops, etc.)

ipconfig /release

(Windows) Forces a client to drop its current DHCP lease

dhclient -r

(Linux) Releases a DHCP lease

What is the PDU for TCP at Layer 4?

Segments

Which DHCP option provides the router's IP address?

Default Gateway (Option 003)

Which flag abruptly ends a TCP session?

RST (Reset)

What range of ports is known as "Well-Known"?

0 - 1,023

Which protocol is connectionless and has an 8-byte header?

UDP

True or False: A DHCP Reservation uses the MAC address.

True

What IP range does APIPA use?

169.254.1.1 - 169.254.254.254

What protocol does IPv6 use instead of ARP?

NDP (Neighbor Discovery Protocol)