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  3. Network+ Practice Tests
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Installing And Troubleshooting Wireless Network, & Properties Of Dhcp

2.2 Given a scenario, install and configure a wireless network.

When installing and configuring a wireless network, you need to remember the following:

Driver Compatibility - It is important to make sure that you have installed the correct device driver for your wireless network adapter.

Low Signal Strength - There are a number of factors that can cause the signal of your access point to deteriorate and the performance of your network to fall under par. Practically any appliance that operates on the same frequency level (2.4 GHz) as 802.11b or 802.11g can cause interference with your wireless network. Be sure to keep cordless phones, microwaves and other electrical equipment at least 1m away from the access point. Try changing channels on the access point and test it out on one of the clients.

Access Point Location - You may also want to try changing the position of your access point antenna to improve performance.

Installing a repeater for a performance boost:

If you're looking for a boost you can always choose to install a repeater. The job of a repeater is to receive the signal, regenerate it and rebroadcast it therefore extending the range of your wireless network. This would sit somewhere between your Access Point and your wireless client.

Changing the Antenna:

Changing the antenna of your access point can increase signal range and overall performance. Typical access points come with a 2dB or 4dB gain antenna but there are one's available with higher gain. Antenna gain is measured in dBi (decibels-isotropic) which basically means how powerful the antenna is and how far it can provide a signal. .

There are three main categories of antennas:

  • Omni-directional - Omni-directional antennas radiate RF in a fashion similar to the way a table or floor lamp radiates light. They are designed to provide general coverage in all directions.

  • Semi-directional - Semi-directional antennas radiate RF in a fashion similar to the way a wall sconce is designed to radiate light away from the wall or the way a street lamp is designed to shine light down on a street or a parking lot, providing a directional light across a large area. Yagi antenna is an example of this type of antennas.

  • Highly-directional - Highly-directional antennas radiate RF in a fashion similar to the way a spotlight is designed to focus light on a flag or a sign. Each type of antenna is designed with a different objective in mind. Phased array antenna is an example of this type of antenna.

Choose which ever antenna type is most suitable.

Other configuration issues that one may need to know are DNS, DHCP, MAC filtering, and encryption settings.

2.3 Explain the purpose and properties of DHCP.

Static Addressing : You can request a static IP address it is one IP address for only one customer and is constant. These are more reliable for VOIP, for hosting gaming websites and to use VPN. Another advantage is that because you IP is static that is it will not be assigned to any other you need not worry of your IP getting blacklisted because of some only else sending SPAM.

Dynamic addressing : When DHCP client boots, it sends out a DHCP discover message. All DHCP servers answer with an offer message that includes an address which is available to the client. client machine typically repeats the discover message several times to make sure it hears from all the servers, then eventually chooses one server The currently active DHCP server is configured by hand to handle and reserve IP addresses and the IP configuration information that goes with them. Addresses are made available in an order that permits a client to have the best chance of getting back the same address it was using most recently. IP configuration information gets automatically configured for your client machine by the DHCP server.

DHCP reservation : If you set a DHCP Reservation the computer you set will get the same IP each time but it will be given out by the DHCP server. DHCP reservation is a permanent IP address assignment. It is a specific IP address within a DHCP scope that is permanently reserved for leased use to a specific DHCP client.

DHCP scope : DHCP scope is the consecutive range of possible IP addresses that the DHCP server can lease to clients on a subnet. These are the primary way for the DHCP server to manage distribution and assignment of IP addresses. These define a single physical subnet on network to which DHCP services are offered.

DHCP lease : DHCP clients get a lease for IP address from server. DHCP server must renew the lease before it expires for the client or client should obtain a new lease. DHCP server database provides an extension of one day after expiration that is database will retain lease information in database for one after expiration this grace period is provided to handle time zone difference , internal clock differences.

2.4 Given a scenario, troubleshoot common wireless problems.

  • Interference :Wireless networks use radio signals to transmit signals and are subjected to interference from many factors. Any electrical device around wireless access point that produce radio waves can cause interference.

  • Signal strength: User always want to connect to the network with highest signal strength. If a user is getting low signal strength either user or WAP can be moved to improve signal strength. Also changing the antenna type can improve signal strength.

  • Configuration: User should not be required to do many configuration changes. Broadcasting SSID will allow user to detect the network and make connection. Any security protocol information and password required by end user should also be communicated in order to make connection.

  • Encryption type: To ensure maximum security for wireless networks highest encryption protocols must be used that are supported by both WAP and clients. Both WAP and clients must be configured with same encryption type.

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