Ch 3 - Addressing

MAC Address

A 48-bit hardware address used to identify a network interface on a local network.

OUI (Organizationally Unique Identifier)

The portion of a MAC address assigned by the IEEE that identifies the hardware manufacturer.

Device Identifier

The portion of a MAC address that identifies the specific network interface/device.

Layer 2 (Data Link Layer)

The OSI layer where MAC addresses operate.

Layer 3 (Network Layer)

The OSI layer where IP addresses operate.

IP Address

A logical address used to identify a device on a network.

RFC 1918 Private IPv4 Addresses

Private IP address ranges: 10.0.0.0/8, 172.16.0.0–172.31.255.255, and 192.168.0.0/16.

Loopback Address (IPv4)

127.0.0.1; an address a device uses to communicate with itself.

APIPA (Automatic Private IP Addressing)

Automatically assigns an IP address when a device cannot reach a DHCP server.

APIPA Range

169.254.0.0/16.

IPv6

A 128-bit IP addressing system.

IPv6 Loopback Address

::1/128; an address an IPv6 device uses to communicate with itself.

IPv6 Link-Local Address

An IPv6 address used for communication on the local network only.

IPv6 Link-Local Prefix

FE80::/10.

IPv6 Global Unicast Prefix

2000::/3; used for publicly routable IPv6 addresses.

IPv6 Multicast Prefix

FF00::/8; used to send data to multiple devices.

SLAAC (Stateless Address Autoconfiguration)

Allows an IPv6 device to automatically configure its own IP address without a stateful DHCPv6 server.

DAD (Duplicate Address Detection)

An IPv6 process that checks whether an address is already being used by another device.

Neighbor Solicitation

An IPv6 message used during DAD to check whether an IPv6 address is already in use.

ARP (Address Resolution Protocol)

Resolves an IPv4 address to a MAC address.

MAC Address vs. IP Address

A MAC address is a Layer 2 hardware address used for local network delivery, while an IP address is a Layer 3 logical address used to identify a device.

SSH (Secure Shell)

A protocol used for secure remote access; uses Port 22 TCP.

SFTP (SSH File Transfer Protocol)

A secure protocol for transferring files; uses Port 22 TCP.

DNS (Domain Name System)

Translates domain names into IP addresses; uses Port 53 TCP/UDP.

NTP (Network Time Protocol)

Synchronizes time between network devices; uses Port 123 UDP.

HTTPS (Hypertext Transfer Protocol Secure)

A secure protocol for accessing websites; uses Port 443 TCP.

RDP (Remote Desktop Protocol)

Allows a user to remotely access and control another computer; uses Port 3389 TCP.

SMTP (Simple Mail Transfer Protocol)

A protocol used to send outgoing email; traditionally uses Port 25.

Secure SMTP Submission

Securely sends outgoing email using TLS/STARTTLS; commonly uses Port 587.

IMAP4 (Internet Message Access Protocol)

An email protocol used to access and manage email on a mail server; uses Port 143.

POP3 (Post Office Protocol version 3)

An email protocol used to retrieve email from a mail server; uses Port 110.

A Record

A DNS record that maps a domain name to an IPv4 address.

AAAA Record

A DNS record that maps a domain name to a 128-bit IPv6 address.

CNAME Record

A DNS record that creates an alias from one hostname to another primary/canonical hostname.

MX Record

A DNS record that specifies the mail servers responsible for receiving email for a domain.

TXT Record

A DNS record that stores text information and is commonly used for SPF and DKIM authentication.

SOA (Start of Authority) Record

A DNS record containing administrative information and zone parameters, including the primary master server.

PTR Record

A DNS record used for reverse DNS lookups that maps an IP address to a domain name.

Forward DNS Lookup

Resolving a domain name into an IP address.

Reverse DNS Lookup

Resolving an IP address into a domain name.

DNS Failure

A problem where domain names cannot be translated into IP addresses.

nslookup

A command-line tool used to query DNS and test whether a domain name resolves to an IP address.

ipconfig /flushdns

A Windows command used to clear the local DNS resolver cache.

ipconfig

A Windows command used to view and manage IP network configuration.

Ping

A command used to test whether a device can communicate with another device over a network.

Can Ping an IP but Not a Domain Name

Usually indicates a DNS problem.