CompTIA Network+ N10-009

Intro to the Internet Protocol

Covering the DoD model, common application protocols and ports, TCP vs UDP, the Internet Layer (IP, ARP, ICMP, IPSec), and data encapsulation.

1.1 Domain 1 Objective

1.4 Domain 1 Objective

20 Quiz Qs

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01 · The DoD Model

Department of Defense Model

The TCP/IP suite was created by the DoD and is a condensed version of the OSI model, consisting of four layers instead of seven. It remains the core architecture of today's Internet.

// Exam Objectives Covered

Domain 1.0: Networking Concepts
1.1 OSI Model Concepts
1.4 Common ports, protocols, services
Process/Application Layer
Host-to-Host Layer (TCP/UDP)
Internet Layer (IP, ARP, ICMP)
Network Access Layer

Process/Application

Combines OSI Application, Presentation, and Session layers. Protocols include FTP, HTTP, DNS, SMTP, and Telnet.

Host-to-Host

Parallels the OSI Transport layer. Protocols include TCP (reliable) and UDP (unreliable/fast).

Internet

Parallels the OSI Network layer. Protocols include IP, ARP, ICMP, and IPSec. Handles routing and logical addressing.

Network Access

Combines OSI Data Link and Physical layers. Monitors data exchange between host and network hardware.

02 · Application Protocols

Process/Application Layer Protocols

These protocols define how applications communicate across the network. It is crucial to know their associated ports and transport protocols for the exam.

FTP (TCP 20, 21)

File Transfer Protocol. Used to transfer files between hosts. 21 is control, 20 is data. Sends in clear text.

SSH / SFTP (TCP 22)

Secure Shell. Replaces Telnet securely. SFTP uses SSH for secure file transfers.

Telnet (TCP 23)

Terminal emulation protocol. Allows remote CLI access. Unencrypted and insecure.

SMTP (TCP 25)

Simple Mail Transfer Protocol. Used for sending email securely or unencrypted.

DNS (TCP/UDP 53)

Domain Name System. Resolves FQDNs to IP addresses. Uses UDP for queries, TCP for zone transfers.

DHCP (UDP 67/68)

Dynamic Host Configuration Protocol. Automatically assigns IP addresses to hosts via DORA process.

HTTP / HTTPS (TCP 80/443)

Hypertext Transfer Protocol. HTTPS uses SSL/TLS for secure, encrypted web traffic.

SNMP (UDP 161/162)

Simple Network Management Protocol. Gathers network statistics. 162 is used for traps.

RDP (TCP 3389)

Remote Desktop Protocol. Allows GUI-based remote connection to another computer.

03 · Host-to-Host Layer

TCP vs. UDP

The Transport layer (Host-to-Host) is responsible for reliable end-to-end communication. TCP provides reliability, while UDP provides speed.

Transmission Control Protocol (TCP)

Connection-oriented (Virtual Circuit)
Reliable, sequenced, and acknowledged
Uses windowing for flow control
Higher overhead

User Datagram Protocol (UDP)

Connectionless
Unreliable, unsequenced, no acknowledgments
No flow control or windowing
Low overhead (fast)

04 · Internet Layer

Internet Layer Protocols

The Internet layer handles logical addressing, routing, and error reporting. It is the core of the TCP/IP stack.

Internet Protocol (IP)

Connectionless protocol providing logical network addressing and routing. Does not guarantee delivery.

Address Resolution Protocol (ARP)

Resolves a known IP address to a MAC (hardware) address on a local network segment.

ICMP

Internet Control Message Protocol. Provides diagnostics and error messages (e.g., Ping, Destination Unreachable).

GRE

Generic Routing Encapsulation. A tunneling protocol that encapsulates various protocols inside IP tunnels. No built-in security.

IPSec (AH/ESP)

Internet Protocol Security. AH provides authentication and integrity. ESP provides confidentiality (encryption) and authentication.

IKE

Internet Key Exchange. Used to negotiate Security Associations (SAs) and manage encryption keys for IPSec VPNs.

10 · Written Lab

Practice Written Lab

Provide the Transport layer protocol and port number for each service. Type your answer (e.g., TCP 22) and press Enter or click outside the field to check.

What are the Transport layer protocol and port number used by SFTP?

What are the Transport layer protocol and port number used by Telnet?

What are the Transport layer protocol and port number used by SMTP?

What are the Transport layer protocol and port number used by NTP?

What are the Transport layer protocol and port number used by LDAP?

What are the Transport layer protocol and port number used by TFTP?

What are the Transport layer protocol and port number used by RDP?

What are the Transport layer protocol and port number used by Syslog?

What are the Transport layer protocol and port number used by SMB?

What are the Transport layer protocol and port number used by IMAP?

What are the Transport layer protocol and port number used by HTTP?

What are the Transport layer protocol and port number used by HTTPS?

What are the Transport layer protocol and port number used by LDAPS?

What are the Transport layer protocol and port number used by SMTPS?

What are the Transport layer protocol and port number used by SSH?

What are the Transport layer protocol and port number used by SQL?

11 · Review Quiz

Test Your Knowledge

20 review questions covering all the chapter material. Select the best answer for each question.

Question 1 of 20

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