CCNA cap. 1-3

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IANA (Internet Assigned Numbers Authority)

Responsible for overseeing and managing IP address allocation, domain name management, and protocol identifiers for ICANN.

ICANN (Internet Corporation for Assigned Names and Numbers)

Coordinates IP address allocation and the management of domain names globally.

IETF (Internet Engineering Task Force)

Develops, updates, and maintains Internet and TCP/IP protocols, documented as RFCs (Request for Comments).

ISOC (Internet Society)

Responsible for promoting the open development, evolution, and use of the Internet.

IAB (Internet Architecture Board)

Responsible for the overall management and development of Internet standards.

IEEE (Institute of Electrical and Electronics Engineers)

Creates standards like 802.3 (Ethernet) and 802.11 (WLAN).

ITU-T (International Telecommunications Union-Telecommunication Standardization Sector)

Defines standards for broadband communications (e.g., DSL), video compression, and IPTV.

EIA (Electronic Industries Alliance)

Best known for standards relating to electrical wiring, connectors, and the 19-inch racks used for mounting equipment.

Layer 7 (Application - OSI)

Contains protocols used for process-to-process communications (user interface).

Layer 4 (Transport - OSI)

Defines services to segment, transfer, and reassemble data; utilizes port numbers.

Layer 3 (Network - OSI)

Provides services to exchange data between identified end devices using logical (IP) addresses.

Layer 2 (Data Link - OSI)

Describes methods for exchanging frames between devices over a common media using physical (MAC) addresses.

Layer 1 (Physical - OSI)

Describes means to manage physical connections for bit transmission (mechanical and electrical).

Application Layer (TCP/IP)

Represents data to the user, plus encoding and dialog control.

Internet Layer (TCP/IP)

Determines the best path through the network (OSI L3 equivalent).

Network Access Layer (TCP/IP)

Controls the hardware devices and media that make up the network (OSI L1 and L2 equivalent).

Transport Layer Data

Encoded application data + Source and destination process numbers (Ports).

Data Link Layer Address Responsibility

Delivering the frame between NICs on the same network.

Network Layer Address Responsibility

Delivering the packet from the original source to the final destination.

Source IP address

The IP address of the sending device, which is the original source of the packet.

Destination IP address

The IP address of the receiving device, which is the final destination of the packet.

Network portion (IPv4) / Prefix (IPv6)

The left-most part of the address that indicates the network the IP address is a member of.

Host portion (IPv4) / Interface ID (IPv6)

The remaining part of the address that identifies the specific device on the network (must be unique).

Subnet Mask (IPv4)

A 32-bit value that differentiates the network portion from the host portion in an IPv4 address.

Default Gateway

The IP address of the router the host uses to access remote networks (including the internet).

Kernel

Communicates between the hardware and software; manages how hardware resources are used to meet software requirements.

Shell

The user interface (CLI or GUI) that allows users to request specific tasks from the computer.

Question

Answer

What is the function of Network Communications Protocols?

To enable two or more devices to communicate over one or more networks.

What are examples of Network Communications Protocols?

IP (Internet Protocol), TCP (Transmission Control Protocol), and HTTP (HyperText Transfer Protocol).

What is the function of Network Security Protocols?

To secure data by providing authentication, data integrity, and data encryption.

What are examples of Network Security Protocols?

SSH (Secure Shell), SSL (Secure Sockets Layer), and TLS (Transport Layer Security).

What is the function of Routing Protocols?

To enable routers to exchange route information, compare path information, and select the best path to the destination.

What are examples of Routing Protocols?

OSPF (Open Shortest Path First) and BGP (Border Gateway Protocol).

What is the function of Service Discovery Protocols?

They are used for the automatic detection of devices or services on the network.

What are examples of Service Discovery Protocols?

DHCP (Dynamic Host Configuration Protocol) and DNS (Domain Name System).

Which Service Discovery protocol discovers services for IP address allocation?

DHCP (Dynamic Host Configuration Protocol)

Which Service Discovery protocol is used to perform name-to-IP address translation?

DNS (Domain Name System)

What do Network Protocols define?

The rules and formats for how messages are exchanged between the source and the destination.

What is required for the Remote Management of a Layer 2 switch?

An IP address (assigned to the Switched Virtual Interface - SVI).

What are the two primary criteria for selecting a Network Medium?

1. The distance the signal can successfully travel; 2. The environment where it will be installed.

Extranet

An extended network that provides secure access to external partners or customers outside the organization.

Intranet

The private, internal network of an organization, accessible only to employees.

The computing model where server software runs on dedicated machines.

Client/Server

Which connectivity protocol uses coaxial cable as the physical medium?

Cable (Cable TV service)

Which high-bandwidth connection runs over the existing copper telephone line?

DSL (Digital Subscriber Line)

Which internet connection is "not suited for heavily wooded areas"?

Satellite (Requires clear line-of-sight)

To which Layer (and protocol) is the Port Number added?

Transport Layer (L4), protocols TCP or UDP.

Which Cisco IOS mode is protected to prevent unauthorized access to configuration commands?

Privileged EXEC mode (protected by the enable password).

Which two Cisco device access interfaces can be secured with passwords?

Console interface (local access) and VTY interface (remote Telnet/SSH access).

During Decapsulation (receiving), what is the first protocol that examines the frame?

Ethernet (Layer 2)

What is the correct order of decapsulation (bottom-up) for receiving a web page?

Ethernet, IP, TCP, HTTP

When a device sends data to a remote network (across a router), the Destination IP is that of…

…the final destination device.

When a device sends data to a remote network (across a router), the Destination MAC is that of…

…the Next-Hop (the router's interface).

Is DSL classified as a narrowband or broadband connection?

Broadband (High bandwidth).

Which layer uses MAC addresses to forward Frames on the local network?

Layer 2 (Data Link)

Which layer uses IP addresses to route Packets between different networks?

Layer 3 (Network)

Which connection type typically has very low bandwidth (max 56 Kbps)?

Dial-up telephone

User EXEC Mode

The first level of access to the CLI after login. Has limited commands (monitoring only). The prompt ends with >.

Privileged EXEC Mode

Accessed with the enable command. Allows advanced monitoring and file management commands (like copy run start). The prompt ends with #.

Global Configuration Mode

Accessed with configure terminal (from Privileged EXEC mode). Changes made here (e.g., hostname) affect the entire device.

Command: copy running-config startup-config

Saves the currently running configuration (in RAM) to the startup configuration (in NVRAM). The new config will load upon reboot.

Command: service password-encryption

Encrypts (using a weak algorithm) all clear-text passwords (e.g., console, VTY) in the configuration file to prevent them from being read with show running-config.

Key: Tab

Completes abbreviated commands or parameters. (E.g., conf t + Tab -> configure terminal)

Key: ?

Provides context-sensitive help (shows available commands or subsequent options).

Key: Ctrl-Shift-6

The "break sequence." Stops executing commands like ping or traceroute.

Key: Up Arrow

Scrolls backward through the history of previously entered commands.

Key: Space Bar

Displays the next screen when the output is long (e.g., show running-config).

Order of Encapsulation (Sending)

Data -> Segment (TCP) -> Packet (IP) -> Frame (Ethernet).

Telnet Sending (1st Step)

Telnet-formatted Data (Application) is provided to the next layer (Transport).

Telnet Sending (2nd Step)

The TCP header is added (creating a Segment).

Telnet Sending (3rd Step)

The IP header is added (creating a Packet/Datagram).

Telnet Sending (4th Step)

The Ethernet header is added (creating a Frame).

IANA (Internet Assigned Numbers Authority)

Organization responsible for IP address allocation and domain name management (DNS).

ISO (International Organization for Standardization)

The largest developer of international standards. Known for the OSI (Open Systems Interconnection) reference model.

ISOC (Internet Society)

Organization that promotes the open development, evolution, and use of the Internet globally.

Packet Destination (IP)

When sending to a remote network, the destination IP is always that of the final host (e.g., HostA).

Frame Destination (MAC)

When sending to a remote network, the destination MAC is that of the default gateway (e.g., RouterB).

RAM (Volatile Memory)

Short-term memory. Contents are lost when the device is powered off. It holds the running-config.

NVRAM (Non-Volatile Memory)

Long-term memory. Retains contents without power. It holds the startup-config.

Running Configuration

The configuration that is actively running on the device, stored in RAM.

SVI (Switched Virtual Interface)

A logical (Layer 3) interface on a Layer 2 switch that allows the switch to be assigned an IP address.

Main purpose of an SVI

To enable remote management of the switch (e.g., via SSH or Telnet).

Default SVI

Interface VLAN 1 (associated with VLAN 1 by default).

IOS Mode Order (Step 1)

User EXEC Mode (Switch>) - The starting point.

IOS Mode Order (Step 2)

Privileged EXEC Mode (Switch#) - Accessed via the enable command.

IOS Mode Order (Step 3)

Global Configuration Mode (Switch(config)#) - Accessed via the configure terminal command.

IOS Mode Order (Step 4 - Final)

Line Configuration Mode (Switch(config-line)#) - Used to configure specific lines (like console 0 or vty).