Page 1 1001 Networking Study Guide for the CompTIA A+ Core Series Exam
How to Prepare for Questions about Networking on the CompTIA A+ Core Series 1001 Test
There are five major topics covered on the 220-1001 CompTIA A+ Core Series exam, Networking is one of them, and about 20% of the questions cover networking concepts and procedures. If you see the notation (scenario) beside a heading below, it means that questions regarding the information in that section will begin with a situation or “scenario” and conclude by asking you for a recommended action or further knowledge about it.
Ports, Protocols, and Purposes
For this exam, you should know the following TCP/UDP port numbers, the protocols that run over those ports, and the primary use for each.
Ports and Protocols
Port numbers are used to distinguish different protocols and services that run over a network.
21 – FTP—File Transfer Protocol; used to transfer files to and from a server
22 – SSH—Secure Shell; used to access remote devices with added encryption
23 – Telnet—used to access remote devices with no encryption
25 – SMTP—Simple Mail Transfer Protocol; used for sending email
53 – DNS—Domain Name System; translates domain names to IP addresse
80 – HTTP—Hypertext Transfer Protocol; standard for communication on the web, used to render pages in web browsers
110 – POP3—Post Office Protocol 3; used for receiving email
143 – IMAP—Internet Message Access Protocol; used for receiving email.
443 – HTTPS—Secure Hypertext Transfer Protocol; secured communication on the web
3389 – RDP—Remote Desktop Protocol; used to connect to remote computers
137-139 – NetBIOS/NetBT—Network Basic Input Output System; used for LAN communication
445 – SMB/CIFS—Server Message Block/Common Internet File System; used for shared access on a network
427 – SLP—Service Location Protocol; used for local service discovery
548 – AFP—Apple Filing Protocol; used for Apple file services
67/68 – DHCP—Dynamic Host Configuration Protocol; used to assign IP addresses to network hosts
389 – LDAP—Lightweight Directory Access Protocol; used to access a directory on network objects
161/162 – SNMP—Simple Network Management Protocol; used to send and receive network management messages
TCP vs. UDP
Transmission Control Protocol (TCP) is a connection-oriented protocol used to send and receive data over a network. Before data is sent, a connection is established with the receiving host. It is considered a reliable protocol because the receiving host acknowledges that it received the data. TCP is used in cases where receiving the proper data is more important than speed.
User Datagram Protocol (UDP) is a connectionless protocol. Data is sent without any assurance that the receiving host is actually receiving the data. For that reason, it is considered an unreliable protocol. The advantage of UDP over TCP is that it is faster.
For this exam, you should understand the basic purpose of network hardware devices and the similarities and differences between them.
These are Layer 3 (network layer) devices that determine the best route for traffic between networks.
Switches are Layer 2 (data link layer) devices that interconnect hosts on a local area network using the MAC address of each host to make decisions about forwarding traffic.
Managed switches are configurable and have features that allow a network administrator to optimize and customize the switch. They typically have better monitoring options than unmanaged switches.
Unmanaged switches are not configurable, sometimes referred to as plug-and-play. Since they cannot be configured, they are designed to allow hosts to connect automatically when plugged into the switch, but that can come at the expense of performance.
An access point is technically any device to which a host can connect in order to access a network. So, while an access point may be a switch, the term usually refers to a wireless access point that allows WiFi devices to connect to the network.
Cloud-Based Network Controller
This is a network appliance that acts as a management console for multiple network access points. It also allows connection of access points to the network without configuring each one individually.
This security appliance filters traffic, permitting or blocking traffic through it based on a configured set of rules and inspection of network traffic.
Network Interface Card
This is an adapter card used to connect a host to the network.
Repeater— a device used to extend a signal being sent to provide additional coverage
Hub— an older technology Layer 1 (physical layer) device that simply connects hosts together. Hubs have no intelligence and do not recognize MAC addresses, so they just send traffic coming in on one port out on every other port
Cable/DSL Modem— a device used to connect to an Internet Service Provider (ISP)
Bridge— a Layer 2 (data link layer) device that connects two network segments and controls traffic moving between them
Patch Panel— a physical panel with multiple connection points used as a central location to interconnect devices and ports on a network. This allows for an organized cabling structure to manage dozens or hundreds of interconnections.
Power over Ethernet (PoE)— a technology, usually incorporated into switches, that delivers power to devices over data lines (Ethernet) rather than having a separate power cord
Injectors: A PoE injector is used to add power to a data cable going to a PoE device like an IP phone or IP camera.
Switch: A PoE switch is a network switch that supplies power to its Ethernet ports to power PoE devices.
Ethernet over Power (EoP)— a technology that uses standard electrical wiring to interconnect Ethernet devices