Study Up: A look at operations and troubleshooting from a CompTIA Network+ perspective
In previous months, we looked at the security and the architecture domains on the new version of the popular CompTIA Network+ certification exam (N10-006). This month we will look at both network operations and troubleshooting as they relate to that exam. Together, these two domains are weighted at 44% of the total exam.
There are a lot of topics these domains touch on (wireless networking and switches being among the largest), but the topics are not nearly as scattered as they are in some of the other domains. In both of these areas, common sense — along with a little bit of knowledge and experience — can be a great tool in helping you pick the right answer on multiple choice exam questions.
What You Need To Know
The following discussion is intended to represent a study guide for this domain. It does not include every topic (space will not allow it), but it covers most of the main topics. In coming months, we will look at some of the other domains and a few of those not touched upon here will be there in an attempt to reduce redundancy as much as possible.
Most of the bullets and tables are very straightforward but if you don’t understand any of the subjects, you would be well-advised to research them further. You should also keep in mind that CompTIA recommends candidates for this certification have CompTIA A+ certification (or equivalent knowledge) and 9 to 12 months of work experience in IT networking.
● 3 defines the carrier sense multiple access with collision detection (CSMA/CD) media access method used in Ethernet networks. This is the most popular networking standard used today.
● A honeypot is a computer that has been designated as a target for computer attacks.
● An antenna’s strength is its gain value. The following table shows a comparison between directional antenna types:
Table 1: Comparing Omnidirectional and Unidirectional Antennas
|Wireless area coverage||General coverage area||Focused coverage area||Omnidirectional allows 360-degree coverage, giving it a wide coverage area. Unidirectional provides a targeted path for signals to travel.|
|Wireless transmission range||Limited||Long point-to-point range||Omnidirectional antennas provide a 360-degree coverage pattern and, as a result, far less range. Unidirectional antennas focus the wireless transmission; this focus enables greater range.|
|Wireless coverage shaping||Restricted||The unidirectional wireless range can be increased and decreased.||Omnidirectional antennas are limited to their circular pattern range. Unidirectional antennas can be adjusted to define a specific pattern, wider or more focused.|
● Full-duplex mode enables devices to receive and transmit simultaneously.
● Half-duplex mode enables each device to both transmit and receive, but only one of these processes can occur at a time.
● IEEE 802.11 wireless systems communicate with each other using radio frequency signals in the band between 2.4GHz and 2.5GHz or 5.0GHz. Of those in the 2.4-2.5 range, neighboring channels are 5MHz apart. Applying two channels that allow the maximum channel separation decreases the amount of channel crosstalk and provides a noticeable performance increase over networks with minimal channel separation
● In-band network device management is local management (the most common method) and out-of-band management is done remotely.
● Multiuser Multiple Input, Multiple Output (MUMIMO) is an enhancement over the original MIMO technology. It allows antennas to be spread over a multitude of independent access points.
● Power over Ethernet (PoE) is a technology that allows electrical power to be transmitted over twisted-pair Ethernet cable. The power is transferred, along with data, to provide power to remote devices. These devices may include remote switches, wireless access points, VoIP equipment, and more. PoE+ is the IEEE 802.3at updated standard to the original 802.3af PoE standard.
● Proxy servers typically are part of a firewall system. They have become so integrated with firewalls that the distinction between the two can sometimes be lost.
● Spanning Tree Protocol (STP) is designed to prevent routing loops from occurring. STP is used with network bridges and switches. With the help of Spanning Tree Algorithm (STA), STP avoids or eliminates loops on a Layer 2 bridge. It is defined as IEEE 802.1d and the more recent rapid spanning tree (802.1w).
● Temperature monitors keep track of the temperature in wiring closets and server rooms.
● The operating systems associated with remote equipment are SCADA (Supervisory Control And Data Acquisition) and ICS (Industrial Control System). A typical configuration includes an ICS server, Distributed Control System (DCS) devices creating a closed network, a remote terminal unit, and a programmable logic controller.
● The VLAN Trunking Protocol (VTP) is a proprietary protocol from Cisco.
● VLAN trunking is the application of trunking to the virtual LAN – now common with routers, firewalls, VMware hosts, and wireless access points. VLAN trunking provides a simple and cheap way to offer a nearly unlimited number of virtual network connections. The requirements are only that the switch, the network adapter, and the OS drivers all support VLANs.
● VLANs are used for network segmentation. 802.1Q is the Institute of Electrical and Electronics Engineers (IEEE) specification developed to ensure interoperability of VLAN technologies from the various vendors.
Table 2: Network Troubleshooting Methodology
|Identify the problem||Gather information|
|Duplicate the problem, if possible|
|Determine if anything has changed|
|Approach multiple problems individually|
|Establish a theory of probable cause||Question the obvious|
|Consider multiple approaches||Top-to-bottom/bottom-to-top OSI model|
|Divide and conquer|
|Test the theory to determine cause||Once theory is confirmed, determine next steps to resolve problem|
|If theory is not confirmed, re-establish new theory or escalate|
|Establish a plan of action to resolve the problem and identify potential effects|
|Implement the solution or escalate as necessary|
|Verify full system functionality and if applicable implement preventative measures|
|Document findings, actions, and outcomes|
● A network’s demarcation point refers to the connection point between the ISP’s part of the network and the customer’s portion of the network.
● A straight-through cable is used to connect systems to the switch or hub using the MDI-X ports.
● A T1 crossover cable is used to connect two T1 CSU/DSU devices in a back-to-back configuration.
● ARP is the part of the TCP/IP suite whose function is to resolve IP addresses to MAC addresses.
● Copper-based media are prone to EMI, whereas fiber-optic cable is immune to it.
● Data rate refers to the theoretical maximum of a wireless standard, such as 100Mbps. Throughput refers to the actual speeds achieved after all implementation and interference factors
● Data signals might also be subjected to crosstalk, which occurs when signals from two cables, or from wires within a single cable, interfere with each other.
● In Windows the tracert command reports how long it takes to reach each router in the path. It’s a useful tool for isolating bottlenecks in a network. The traceroute command performs the same task on UNIX and Linux systems.
● ipconfig /all is used to display detailed TCP/IP configuration information.
● ipconfig /renew is used on Windows operating systems to renew the system’s DHCP information.
● ipconfig shows the IP configuration information for all NICs installed in a system.
● Many factors cause EMI, including computer monitors and fluorescent lighting fixtures.
● nbtstat is used to display protocol and statistical information for NetBIOS over TCP/IP connections.
● netstat is used to view both inbound and outbound TCP/IP network connections.
● The ifconfig command is the Linux equivalent of the ipconfig command.
● The netstat -a command can be used on a Windows-based system to see the status of ports.
● The nslookup command is a TCP/IP diagnostic tool used to troubleshoot DNS problems.
● The weakening of data signals as they traverse the media is called attenuation.
● When it comes to wireless, distance from the AP is one of the first things to check when troubleshooting AP coverage.
● When looking for client connectivity problems using ipconfig, you should ensure that the gateway is set correctly.
● When you have two dissimilar types of network media, a media converter is used to allow them to connect.
● You can ping the local loopback adapter by using the command ping 127.0.0.1. If this command is successful, you know that the TCP/IP suite is installed correctly on your system and is functioning.
Table 3: 802.11 Wireless Standards
|IEEE Standard||Frequency/Medium||Speed||Topology||Transmission Range||Access Method|
|802.11||2.4GHz RF||1 to 2Mbps||Ad hoc/infrastructure||20 feet indoors||CSMA/CA|
|802.11a||5GHz||Up to 54Mbps||Ad hoc/infrastructure||25 to 75 feet indoors; range can be affected by building materials||CSMA/CA|
|802.11b||2.4GHz||Up to 11Mbps||Ad hoc/infrastructure||Up to 150 feet indoors; range can be affected by building materials||CSMA/CA|
|802.11g||2.4GHz||Up to 54Mbps||Ad hoc/infrastructure||Up to 150 feet indoors; range can be affected by building materials||CSMA/CA|
|802.11n||2.4GHz/ 5GHz||Up to 600Mbps||Ad hoc/infrastructure||175+ feet indoors; range can be affected by building materials||CSMA/CA|
|802.11ac||5GHz||Up to 1.3Gbps||Ad hoc/infrastructure||115+ feet indoors; range can be affected by building materials||CSMA/CA|