Network+ Exam Objectives 2.4

2.4 Given a scenario, differentiate and implement appropriate wiring standards.

• 568A – 568A is one of the two commonly used standardized 8-wire data network jacks and is commonly used residentially. Generally 568A should be used in residential areas as long as the two inner pairs of 568A are wired the same as a two-line phone jack and that components are internally wired for that specific type.

• 568B – 568B is the second commonly used standardized 8-wire data network jack. T568B is the most prevalent for commercial installations.

• Straight vs. cross-over – Per 10BASE-T and 100BASE-TX Ethernet standards, a wire pair is needed in order for transmission in each direction. This means that the transmit pair of every device has to be connected to the receiving pair of the device on the opposite end. When an end device is connected to a hub or switch, the crossover is internal and takes place in the hub or switch.

In some cases, a device may be connected to another device directly without the use of a hub or switch. When this occurs the crossover must be done externally and the pairs are swapped in the cable. A crossover cable have to be used in order to connect two internally crossed devices, such as two hubs or two switches so that the internal crossovers are nullified.

• Rollover – Sometimes referred to as a Cisco console cable, a rollover is a null modem cable that is most often used to connect a terminal to a router’s console. Rollover cables are generally flat and are often a shade of blue. The name comes from the fact that the pinouts on one end are reversed from those on the other side.

• Loopback – A loopback usually involves the procedures/methods of routing electronic signals, data streams, and other data flows from the originating location back to the same source without any type of intentional modification or processing. Loopback is generally used to test transmission infrastructure.

TCP/IP supports a loopback device which creates a virtual network that is not connected to any sort of hardware. The loopback is implemented through software that is integrated into the systems internal network. Loopback interfaces are used for communication purposes between network software on a computer and server software on the same terminal.

Network+ Exam Objectives 2.3

2.3 Identify common physical network topologies.

Topology is simply how a network is organized. Physical topology involves how a network is physically mapped. Topology also involves logical topology, which considers how data flows and is processed on a network. Generally physical and logical topologies are mapped in the same way, but in some network topology types the two can be different.

• Star – Star topology is a network when all nodes in a network are connected to a centralized point such as a switch or hub. Star topology is often used with 10Base10 and 100BaseTX. Star topology is inexpensive, easy to maintain, very reliable, and is one of the most commonly used physical network topology today. Star topology is prone to collisions and other security problems.

• Mesh – Mesh network topology is very different from most topologies in the fact that all parts of the network can connect to each other through multiple hops. This means that broken paths can be easily rerouted as alternative paths can be used. A fully connected mesh network occurs when every other network node is connected. Mesh topology is generally used in WANS and most importantly the Internet. Mesh topology provides high fault tolerance so if a node were to fail, the network can still run. However mesh topology is extremely complicated as well as costly to set up and maintain.

• Bus – Bus topology is quite simple: the network is set up in a linear, straight sequence of nodes that is terminated in both ends. Bus topology is used with both Thinnet and Thicknet. Though simple, bus topology is rarely used today because it is unreliable. If a node within the network fails, the entire network will not work. Bus topology is pretty much obsolete in today’s world.

• Ring – In ring topology, packets travel to the next mode within the ring formation. This means that only one node at a time has the token. Ring topology in the logical fashion is often used in ordinance with physical star topology. Ring topology is used in Token Rings as well as FDDI. Ring topology is great in the fact that collisions rarely occur however the topology is expensive and hard to troubleshoot. The topology is prone to failure and if one of the nodes fails, the entire network fails.

• Point to point – Point to point topology is when a switch is used in order to provide for many point-to-point circuits through microsegmentation. This allows for each node to have a set circuit as well as access to full duplex connections.

• Point to multipoint – In point to multipoint topology, a hub is used which then creates a network circuit that divides the bandwidth from the hub for each node that is connected. Point to multipoint topology is used in ATM, X.25 networks, wireless internet, and Frame Relay links.

• Hybrid – Hybrid networks are simply those networks that use a combination of two or more topologies. With this combination the outcome does not meet any of the commonly used topology types. An example is two connected star networks or a star ring network.

 

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CompTIA Network+ Exam Objectives 2.2

 

2.2 Identify common connector types 

Cables are a necessary part of a functioning network. However, there is a variety of cables that are used for various different purposes. Some cables are used more commonly than others but each of them has a specific function within a network. It’s important to know the common cable types, their basic functions, and the properties and specifications associated with each connector type.

• RJ-11 – Registered jack (RJ) cables are used for telephone connections and are designed to be able to connect two pairs of wires. An RJ-11 is one of the most commonly used connect in today’s world as it is found in homes, businesses, and most locations that have a phone connection. RJ-11 connectors are needed in the case of a network that is running a dial-up connection.

• RJ-45 – The RJ-45 is the most commonly used connector that can connect four pairs of wires but generally only contains two of them. It is often used to connect NICs to a hub or a switch. An RJ-45 cable can also be used to connect network devices.

• BNC – The Bayonet Neill-Concelman (BNC) connector is not widely used today for networking purposes but it is still an important connector to know of. The BNC connector is a terminating coaxial cable that can also be used for radio antenna connections, avionics, RF signal connections, digital and analog signals and others. The connector is used by pushing in and then locking it in place.

• SC – The standard connector (SC) connector is a fiber-optic connection that has a push-pull mechanism that is needed to lock it in place. This function makes the connector easy to insert as well as to remove. Usually SCs are used with multimode fiber-optic connectors as a backbone segment on a network.

• ST – The straight tip (ST) connector is a fiber-optic connector that has a socket that locks in place using a bayonet lock. The ST is today’s standard for fiber-optic cabling.

• LC – The LC connector was created by Lucent and was made to be a mimic of the SC connector just a smaller version of it. LC is widely used in Telco environments.

• RS-232 – RS-232 is a standard connector used for serial binary data signals that have to be connected between Data Terminal Equipment (DTE) and Data Circuit-terminating Equipment (DCE). You’ll find RS-232 most commonly used in computer serial ports.

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CompTIA Network+ Exam Objectives 2.1

2.1 Categorize standard cable types and their properties 

As networking and the processes behind it have continued to change and advance, the cables needed for networking has changed as well. No longer do we use copper wired cables. Instead we use cables with glass fibers that are faster and more reliable.

Type:  The type of cables you choose to use within your network will be determined by what you plan to use your network for and the capabilities that you need out of it.

• CAT3, CAT5, CAT5e, CAT6 – In twisted-pair cables the tighter the twist is the faster the information can be transmitted. CAT3 cables have a maximum speed of 10Mbps, CAT5 of 100Mbps, CAT5e 1000Mbps and CAT6 1000Mbps.

• STP, UTP – Shielded twisted pair (STP) cables are much like UTP cables except that is a foil shield covering the wires for added protection from magnetic interference. The foil shield is only effective if the wires are grounded therefore making use of STP cables much more complex.

UTP (unshielded twisted pair) cables are extremely common in today’s world. UTP is much easier to install when compared to STP cables and is often used for distribution and access purposes. Since the pairs of wires within the cable are twisted, electrical interference is rare.

•   Multimode fiber, single-mode fiber – Multimode fiber cables (MMF) use light in order to communicate a signal, however with these cables the light is dispersed onto many different paths, travels through the core and is then reflected back through cladding, a material used to line the core and focus the light source back onto it. Multimode fiber cables can be used for high-speed bandwidth up to 3,000 feet. Multimode cables are best used in small areas.
   
•  Single-mode fiber – Single-mode fiber (SMF) cables are a high-speed high-distance media due to its design using glass fiber to carry the signals. Lasers are the most commonly seen light source when it comes to SMFs but LEDs can be used as well. Single-mode fibers are perfect for long distance communication.

• Coaxial – Coaxial cables are designed with an inner core wire with an outer braided insulating wire. During the 1980s, coaxial cables were used as the backbone of network segments as well as the cable needed to connect computers on a bus topology network. Though popular decades ago, coaxial cables are not commonly used today for these purposes but the cables are still used for connecting NICs and modems for broadband Internet access.

•    RG-59 – RG-59 is a coaxial cable that is commonly used for low-power video signal connections. It is usually found in digital and satellite receivers along with VCRs. RG-59 cables are highly inexpensive cables and are sufficient for short distance use up to 6 feet. RG-59 is best suited for shorter distances as it is known for its high-frequency losses over long distances.

•   RG-6 – RG-6 is another type of coaxial cable that is similar to the RG-59 but is more suitable for longer distances. It is widely used for many different commercial and residential purposes including cable television. In this situation RG-6 is used as a distribution coax in order to route the television signals to homes. Nowadays the RG-6 is the CATV standard cable.

• Serial – Serial cables are cables that are designed to be able to transfer information between two serial communication devices. Serial cables are fitted to use 9 or 25 pin connectors but other kinds of connectors can be used successfully.

• Plenum vs. Non-plenum – Plenum cables are those that are put in the plenum spaces of building or those that are set aside for air facilitation and circulation including heating and cooling systems. Plenum cables are able to provide pathways for conditioned and/or heated return airflows. Often times the space between the ceiling and dropped ceiling is considered to be plenum space. Usually this space, especially in homes or office buildings, is used for wiring a computer and/or telephone network.

Any type of cable that is run between floors in non-plenum areas are known as non-plenum cables. Sometimes known as riser cables, non-plenum cables can too be used for the same purposes but cannot be used to replace a plenum cable in a plenum location due to fire safety and hazard.

Properties:

•  Transmission speeds – Each cable has a different transmission speed which is determined by the overall number of bits sent per unit time, usually seconds or minutes.

• Distance – Some cables are designed to be used for both short and long distances. The ideal distance for certain cables will determine

•  Duplex – In networking and communications, duplex deals with a system that is made up of two connected devices that are able to communicate in both directions.

• Noise immunity (security, EMI) – Noise immunity deals with how well a cable is able to perform its set job when noise (interference) is present. The higher level of noise where a cable can maintain its operational ability, the higher its noise immunity is.

•  Frequency – Often expressed in Hertz (Hz) frequency measures the number of waves that pass a certain point in a set unit time.

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Network+ Exam Objectives 1.7

1.7 Compare the characteristics of wireless communication standards

Within the last decade, wireless communication and its uses have continued to grow and advanced. Nowadays computers, cell phones, PDAs, and more all make use of wireless communication. Today’s wireless communications continue to be engineered to be even faster to meet the fast-paced world of today, with growing networks classified as 3G, 4G, and even 5G. Security of wireless communication is also a growing concern that engineers all over the world continue to study and upgrade.

802.11 a/b/g/n

802.11 is the IEEE specification that is used by wireless LAN communications. 802.11 is needed in order to specify an interface between two wireless clients or communication between a wireless client and a base station. Today’s 802.11 is much different from those versions used in the past.

•   802.11a – 802.11a, which is not very widely used today, requires a 5GHz radio band and is capable of transmitting upwards to 54Mbps. To increase bandwidth, 802.11a uses orthogonal frequency division multiplexing.

• 802.11b – 802.11b is one of the more commonly used wireless communication standards. It is able to transmit up to 11Mbps with fallback rates of 1Mbps, 2Mbps, and 5.5Mbps. It uses a 2.4GHz band with DSSS.

•   802.11g – 802.11g is often referred to as an enhancement to 802.11b. It also uses DSSS on a 2.4GHz band and is able to transmit with speeds upwards of 54Mbps. 802.11g is just as commonly used, if not more commonly used than 802.11b.

• 802.11n – 802.11n too uses DSSS on a 2.4GHz band. It is an upgrade and enhancement of 802.11g and is able to transmit 600Mbps but devices today generally only use 300Mbps. 802.11n is not very widely used, yet.

Authentication and encryption

The authentication and encryption of wireless communications has been a long-time issue that has yet to be perfected. However, as newer and more advanced technologies continue to be created, the authentication and encryption aspect of wireless communication has grown stronger. 

•  WPA – Wi-Fi Protected Access (WPA) was created in order to fix some of the security flaws and weaknesses with WEP. WPA offers dynamic encryption key generation, meaning that the keys are given on a per-use and per-session basis. WPA also offers an integrity-checking technology through the temporal key integrity protocol (TKIP) which adds a 128-bit encryption key which was secure for awhile but in today’s world is seen as highly unsecure.

•   WEP – Wireless Equivalent Privacy (WEP) is one of the first attempts at creating secure wireless communications on 802.11 networks. To provide security, WEP was designed to encrypt the data transfer. However, the flaw existed in the fact that the technology used to encrypt the data transfer was not encrypted. WEP also only works on the lower end of the OSI model in the data link and physical layers and cannot be used for end-to-end security purposes. The encryption key used with WEP is static and shared and there is no way to authenticate users, leaving them prone to spoofing attacks.

• RADIUS – Remote Authentication Dial In User Service (RADIUS) provides centralized authentication, authorization, and accounting management when computers are connected to a network. RADIUS runs in the application layer using UDP transport methods. Using RADIUS, there is the ability to authenticate users or devices before giving them network access, authorize those users and/or devices for specific network services, and to account for the usages per user/device. RADIUS too is considered to be insecure.

• TKIP – Temporal Key Integrity Protocol (TKIP) was created as a solution for replacing WEP without having to replace hardware. Using TKIP, the technology was able to implement a key mixing function that combined a secret root key with an initialization vector. TKIP also allowed for protection against replay attacks since out of order packets were rejected at access point. TKIP also introduced the 64-bit message integrity check (MIC). TKIP also ensures that every data packet received has its own unique encryption key. However TKIP is still prone to attacks.

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Network+ Exam Objectives 1.6

1.6 Explain the purpose and properties of routing

To keep it simple, think of routers as specialized computers that are designed for two main functions: the ability to deliver a packet to a network host and the task of consulting set routing tables that provide specific directions as to where a packet needs to go.

• IGP vs. EGP – Most routing protocols used today are IGP and are designed to work within a single autonomous system. When it comes to talking about EGP, it’s important to remember that BGP is the only EGP that is commonly used in today’s world.  Make note that BGP works between autonomous systems such as connecting to the internet.

• Static vs. dynamic – It’s important to remember that static notates that the routing configuration has been done by a system administrator. Statically configuring routers completely is possible, but it is definitely the hard way to do things because each and every route would have to be reevaluated and changed accordingly.

With dynamic routing, the routers and routing protocols do all of the work therefore a system administrator is not needed as much. Since all routers are configured to be able to exchange information regarding data packets and the needed routing paths, dynamic routing is suitable for all routing protocols but some are able to perform dynamic routing much better than others. In the end it’s much more effective and efficient when looking at static routing.

• Next hop – A packets origination is never a worry when dealing with routing protocols. When it comes to routing, the routers are only worried with where the packet has to go, also referred to as the destination header. With the information provided in a destination header, the router can decide whether or not it can deliver the packet or if it needs to be delivered to another router for further network movement.

In the event that a router cannot deliver a packet itself, it will consult its routing table to determine where the packet needs to go next. When looking at the routing table, the information given will tell the router the interface that the packet needs to go to next. This next interface is usually known as the next hop. The movement of the packet from one interface to another is a hop.

• Understanding routing tables and how they pertain to path selection – When consulting routing tables, routers automatically know where a packet needs to go. By virtue of the table, a router knows exactly where a packet needs to be delivered in order to reach its final destination. When looking at routing tables, it’s important to remember that a packet’s destination determines the path it travels. A packet needing to get to a 172.16.0.0 destination will not be sent on the same interface as a packet needing to get to a 192.16.1.0 destination.

• Explain convergence (steady state) – Convergence occurs after a change has been made and everything involved is in agreement after the change. An example is adding a new router to a steady state network. If a system administrator adds a new interface to a network router, all of the routing protocols have to examine the new path and decide if the newly created path is more efficient than the one that is already being used. Every router on the network will perform this action which of course disrupts the steady state of the network.

Once all is said and done, the network activity will calm and return to a steady state. This downing of activity is convergence. 

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Network+ Exam Objectives 1.5

1.5 Identify common IPv4 and IPv6 routing protocols

It’s important to remember that a routed protocol is not the same as a routing protocol. When thinking about routed protocol, the first and only thing that should come to mind is IP, the most widely and commonly used routed protocol today. With IP, routers are able to identify and deliver data packets.

In some cases a data packet may not belong on a certain network. When this occurs, routers use routing tables to decide what should be done with the packet. The routing tables used are created using specific routing protocols. To be successful in section 1.5, it’s important to know of the basic routing protocols and how each of them functions on a network.

• Link state Link state is the most commonly used type of routing protocols. These routing protocols are able to identify information about a packet including what it’s connected to, where it is, the speed of it, and so on. Using link state protocols, all of this information is sent in LSAs (link state advertisements) and using the LSAs, routers are able to build a network map. Each router will have the same map and is therefore able to decide what should be done with the packet.

•  OSPF – Open shortest path first (OSPF) is the go to link state routing protocol as it is suitable for all network types and sizes. Looking at its name, it’s safe to assume that the protocol is an open protocol that uses the SPF algorithm and isn’t proprietary. OSPF is so widely used because it is able to converge on a network even when a sudden change occurs which means that when a routing table needs to be changed, the action can be completely quite quickly when using OSPF. Usually the change takes no more than a few seconds.

• IS-IS – Intermediate system to intermediate system (IS-IS) is not a commonly used link state routing protocol today. IS-IS too uses the SPF algorithm in order to decide where a packet should be delivered but the system uses a complex level system in order to obtain network topology. IS-IS, in the past, has been used by large service providers but rarely government or commercial networks.

• Distance vectorThe name describes the basic function of distance vector protocols. In this case distance refers to how far a packet needs to go and vector goes along with determining the direction of said packet. Distance and direction are both observed and compared against routing tables when using distance vector protocols.

• RIP – Routing information protocol (RIP) today is mostly obsolete though it does stand as the first distance vector ever created and used, but today it has since been replaced by RIPv2, OSPF, and other routing protocols. RIP works by having the routers broadcast the information they know regarding the network every 30 seconds, the main fallback with the protocol. RIP is also classful and the hop count used is severely flawed, therefore making it unusable for efficient network management.

• RIPv2 – Routing information protocol version 2 (RIPv2) is the more improved version of RIP. The protocol was able to fix some of the biggest flaws with RIP but it still does not perfect the original protocol. RIPv2 does not broadcast every 30 seconds and instead uses multicast addressing which makes the protocol much more efficient. Unlike RIPv1, RIPv2 can be made to be classless which means it can be used on a more complex network. The only flaw that exists is the fact that RIPv2 still uses a hop count.

• BGP – Border gateway protocol (BGP) is not a widely discussed topic on the Network+ exam. For your own knowledge, it may be important to know that BGP can be used on an autonomous network where all network devices are under the same control no matter of their location. Connecting to the Internet is an example of BGP.

• Hybrid There is only one notable hybrid routing protocol worth knowing for the Network+ test, EIGRP. As a hybrid routing protocol, EIGRP is truly a distance vector but it acts and works like a link state protocol.

• EIGRP – Enhanced interior gateway routing protocol, combines both technologies of distance vectors and link state protocols. EIGRP is a very advanced protocol because it is a hybrid and makes great use of the fast convergence of link state protocols. EIGRP does not use a hop count; instead it uses a metric that involves the bandwidth and delay of a connection, meaning how much time traffic needs to travel on a network path. The only downfall with EIGRP is that it is a Cisco proprietary and can only be used on Cisco routers and switches.

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