N10-009 Network Implementation Study Guide for the CompTIA Network+

General Information

This is study material for the CompTIA Network+ N10-009 exam, which replaces the old Network+ N10-008 exam as of December 20, 2024. Be sure you are studying for the right test.

On the CompTIA Network+ N10-009 exam, you will find that about one-fifth (20%) of the questions concern implementation concepts. About half of these questions begin with a scenario, so you’ll need to be able to identify terms and concepts while addressing active situations using your knowledge of implementation procedures.

Routing Technologies

Within a network environment, multiple protocols can be used for routing, depending on the network’s requirements. Routing is the process of directing packets between networks and subnetworks using routers. IP routing is the most commonly used routing technology, which directs packets based on IP addresses. You will need to be able to compare and contrast common routing technologies.

Static Routing

Static routing is a routing protocol that uses pre-configured routing data to route packets to their destination. It can only be changed manually, so static routing does not scale well.

Dynamic Routing

Dynamic routing is a routing process that forwards packets to their destination based on the current routing environment. Dynamic routing is adaptive and is based on continual communication between routers using the same protocol to share information. Dynamic routing can use either interior gateway protocols (IGPs), which are used within an autonomous system (AS), or exterior gateway protocols (EGPs), which are used outside of or between more than one AS.

Border Gateway Protocol (BGP)

BGP is an EGP that is used by the internet to determine the best route based on complex algorithms that evaluate path vectors, rather than distance vectors, making it a hybrid protocol. BGP can connect multiple IGPs by sharing its routing information base (RIB). A RIB contains information on hop-by-hop paths to different autonomous systems, also known as an AS path, as well as network prefixes and IP addresses used to get to the next AS, known as the next-hop attribute.

Enhanced Interior Gateway Routing Protocol (EIGRP)

EIGRP is a classless distance-vector protocol that sends subnet mask information with its routing advertisements and updates. EIGRP is also a hybrid protocol due to its incorporation of link-state characteristics as well as distance-vector protocols. EIGRP creates neighbor tables, which it synchronizes upon startup, and only triggers routing updates when a change in topology occurs, which is a link-state characteristic. When a routing update is triggered, EIGRP sends the best route routing information based on distance and hop count, which is a distance-vector characteristic.

Open Shortest Path First (OSPF)

OSPF is an open-source link-state IGP protocol that uses a routing table based on the results of Dijkstra’s algorithm to create a shortest-path tree to identify the most effective routing path. OSPF is capable of using both IPv4 and IPv6 addresses kept in separate routing tables. OSPF does not have a maximum hop count and supports classless routing.

Route Selection

Route selection is the process of choosing a route to send packets from the sending location to the target destination. During the route selection process, numerous factors may come into consideration for effective routing.

Administrative Distance (AD)

The AD is a measurement of route trustworthiness measured from 0 to 255, with the higher numbers indicating less trustworthy routes. When a router encounters more than one route to a destination, the first criterion the router uses is the AD to determine which route to take. The route with the lowest AD will be used. If both routes have the same AD, then the next criterion that is considered is the hop count.

Prefix Length

The prefix length is the leading bits in the IP, which are used to define the network portion of the IP address. Higher prefix lengths result in more specific network routes. For example, in the IPv4 address 192.168.1.0/24, the prefix length is 24.

Metric

A metric in route selection is a value that is used to determine the best routing path available. Commonly used route metrics are hop count (how many devices, mostly routers, will be traversed), the speed of the link, and the time delay between connections.

Address Translation

Address translation is the process of taking a logical address (IP address) and translating it into a physical address (media access control [MAC] address) using the Address Resolution Protocol (ARP). ARP is used to map the hardware address of an interface from an IP address, which is then stored in the ARP cache.

Network Address Translation (NAT)

NAT is a protocol allowing a private IP-addressed device to communicate with a public IP address by translating the private IP to a public IP.

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Port Address Translation (PAT)

PAT is an extension of NAT that enables devices assigned to a specific private IP address port number to access a public IP address via that port number.

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First Hop Redundancy Protocol (FHRP)

FHRP is a virtualization technique that is used to create a default gateway that allows multiple routers to behave as a single default gateway through a VIP address. There are three commonly used methods of FHRP implementation, including the Cisco-proprietary Hot Standby Router Protocol (HSRP), the Gateway Load Balancing Protocol (GLBP), which also offers load balancing capabilities, and the Virtual Router Redundancy Protocol (VRRP), which is a widely supported industry standard.

Virtual IP (VIP) Address

A VIP address is an IP address that does not correspond to a physical hardware device but, rather, only exists virtually. Since VIP addresses are not tethered to a physical device, it can rotate between nodes in the network as needed.

Subinterfaces

A subinterface is a virtual interface created by dividing a single interface, such as a router, into multiple logical interfaces. This allows a single device to create and run multiple IPs and subnets on the device at once.

Switching Technologies and Features

Ethernet switching, also known as network switching, allows for connecting multiple wired devices onto a LAN, which provides a communication method between the devices. While switches can be deployed to create a LAN for a specific geographic area only (such as the floor of an office building), most switches create logical LANs, or virtual LANs, to create separation between groups of devices that is not restricted by physical location. For the CompTIA Network+ N10-009 exam, you will need to be able to understand, configure, and deploy common Ethernet switching features based on a given scenario.

Virtual Local Area Network (VLAN)

A VLAN is a group of devices logically connected on a switch that creates smaller broadcast domains, essentially functioning as subnets.

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VLAN Database

A VLAN database is where all the information pertaining to the VLANs on a switch is stored and managed. A VLAN database includes information such as the VLAN ID, port assignment, and names, which are used to track segments logically through a physical network.

Switch Virtual Interface (SVI)

The SVI is the logical Layer 3 interface that connects the VLAN to the routing component of the switch. An SVI provides routing between VLANs by acting as a default gateway, resulting in decreased latency, improved cost efficiency, increased scalability, and simplified configuration and management.

Interface Configuration

VLAN interface configuration refers to the process of creating and configuring a VLAN, including the assignment of IP addresses, port assignments, and traffic type.

Native VLAN

A native VLAN is a VLAN that is used to transmit untagged VLAN traffic over a specific VLAN on a trunk. The native VLAN allows for the forwarding of any Layer 2 frames, tagged or untagged, allowing for communications between devices that do not support VLAN tagging, such as a hub.

Voice VLAN

A voice VLAN, also known as an auxiliary VLAN, is a separate LAN designed to carry voice traffic only. By separating the VLANs, priority of transmission can be assigned to voice data to ensure quality of service. Also, by separating the data VLAN and the voice VLAN, both can be connected to a single port, with the two VLANs running on top of one another and bandwidth assigned separately.

802.1Q Tagging

Port tagging was created by the Institute of Electrical and Electronics Engineers (IEEE) as a standardized method for frame tagging, which can be used for communication between different switch manufacturers. Port tagging, or the 802.1Q protocol, inserts an 802.1Q field into a frame that contains 16 bits of data, 12 of which indicate the VLAN ID. Using 802.1Q, any switch with the corresponding VLAN ID can communicate with other switches with the same VLAN ID.

Note: Port tagging is used across trunk links and internally only.

Link Aggregation

Port aggregation is the process of combining multiple Ethernet links into a single logic link, called a port channel, providing redundancy and increased system performance by supplying numerous links through which data can be sent under a single logical link. Port aggregation can be configured manually or through the use of channel negotiation protocols, such as the Port Aggregation Protocol (PAgP), which is a Cisco proprietary protocol, or the Link Aggregation Control Protocol (LACP).

LACP is a protocol through which ports are aggregated according to the IEEE 802.1ad standards. Both LACP and PAgP monitor the port channels and the links contained on the channel to ensure compatibility of speed, duplex settings, and VLAN, as well as to manage link additions and removal of failed links.

Speed

Speed refers to how much data can be transmitted over a link, such as 10 Mbps or 100 Gbps. With port aggregation, the speed of the connected links should match for optimal performance, which can be configured manually but is more commonly autosensed for speed match.

Duplex

Duplex refers to a point-to-point communication method between two devices that can communicate back and forth between each other. With port switching, the duplex can be either half-duplex, where data can only flow in one direction at a time, or full-duplex, which is capable of sending and receiving simultaneously. For port aggregation, the duplex settings of the links in the port channel need to match for proper functionality.

Spanning Tree Protocol (STP)

STP is designed primarily to seek out and prevent Layer 2 loops from occurring by using the spanning tree algorithm (STA) to create a topology using the bridge protocol data units (BPDUs) provided by connected switches. It then searches that topology for redundant links and destroys them, leaving only the links identified by STP as the best links.

Maximum Transmission Unit (MTU)

The MTU is the maximum size of a frame, packet, or segment in bytes or octets that can be transmitted across a data link. MTUs are limiters associated with Layers 2, 3, and 4 of the OSI model.

Jumbo Frames

A jumbo frame is an Ethernet frame with a payload over the standard Ethernet MTU of 1,500 bytes. VLAN ports can be configured to accept jumbo frames but require speeds of at least 1 Gbps.