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Wireless Final

QuestionAnswer
What is a Beacon Frame? Beacon frames are transmitted by the Access Point (AP) in an infrastructure BSS. Beacon frames are transmitted periodically to announce the presence of a Wireless LAN.
What is the purpose of the ACK frame? ACK is the acknowledge frame sent to confirm receipt of a frame.
3 Organizations involved with wireless communication? IEEE - standardization, WiFi - interoperability, FCC - regulations (or country equivalent)
What are the 2 unlicensed RF bands which we use? 2.4 GHz ISM band and the 5Ghz UNII band
What is the ISM band? Industrial, Scientific, and Medical. 2.4GHz
What is the UNII band? Unlicensed National Information Infrastructure, 5GHz.
What is SOHO? Small Office / Home Office, does not require the same infrastructure as Enterprise.
What is FHSS? Frequency Hopping Spread Spectrum. Old method for data transmission. (1-2 Mbps).
What is DSSS - HR/DSSS? (High Rate) Direct Sequence Spread Spectrum. 1-2Mbps for normal. 5.5-11Mbps for HR.
What is OFDM? Orthogonal Frequency Division Multiplexing. 6-54Mbps. 5GHz.
What is ERP-OFDM Extended Rate Physical Orthogonal Frequency Division Multiplexing. 6-54Mbps. 2.4GHz.
What is MIMO? Multiple Input Multiple Output. Uses multiple receiving and transmitting antennas.
What is HT-OFDM? High Throughput Orthogonal Frequency Division Multiplexing. Up to 600Mbps, using MIMO.
What is 802.11e? QoS support for wireless. Introduces HCF - Hybrid Coordination Function involved with QoS.
what is 802.11i? Advanced security solutions for wireless LAN. To fix broken WEP feature.
Which layers of OSI model does wireless networking function? Layer 1 + Layer 2. SOME layer 3 as well.
Are the access points we use half or full duplex? All APs are Half-Duplex.
What is the purpose of a Bridge? Connect two or more WLAN together.
What is the purpose of a Repeater? Extend the radio frequency cell, throughput is reduced by 50%.
How many IP addresses does an AP get? 1 IP placed on the BVI.
What is guest-mode? When guest mode is set on the dot11 ssid configuration it will be broadcast so it is easy for people to find. Only 1 ssid can use guest mode.
Do you configure VLAN in 'dot11 ssid' or 'int dot11radio' configs? Vlan is bound in the 'dot11 ssid' configuration.
In which configuration do you set the channel for the AP? int dot11radio
In which configuration do you set the station-role? int dot11radio
If you want to set sub interfaces of the AP into VLAN 20 and make it native, what commands do you use? encapsulate dot1q 20 native bridge-group (#)
How do you verify the SSID and BSSID? show int dot11radio
How do you verify the RF power and channel? show controllers
What is the BSSID? Each BSS is uniquely identified by a Basic Service Set identification, the MAC address of the AP.
What is the SSID/ESSID? Service Set Identifier, normally a human-readable string and thus commonly called the "network name".
What is the BSS? Basic Service Set. In infrastructure mode, a single access point (AP) together with all associated stations (STAs) is called a BSS.
What is the BVI? Bridge Virtual Interface. You can set an IP to this and it connects to both the wired and wireless interfaces of the AP.
What is STA? Wireless Station, any end device that connects through 802.11
What is DS? Distribution System. Interconnects BSSs to LANs. Can be wireless (bridge) or wired (switch).
What is BSA? Basic Service Area, also known as Cell. Defined by the signal strength.
What is ESS? Extended Service Set. ONE or more BSSs interconnected by a DS. Identified by the (E)SSID.
What is IBSS? Independant BSS. Self-contained network, also called Peer-toPeer, ad hoc. NO DS.
What is Multi-Channel Architecture? Seperate channel per cell, reduce cell size + use more cells for increased capacity.
What is Single Channel Architecture? Same channel per cell, channel layer for capacity.
What is Sectorized Array Arch? Sectored antenna system, add sectors for capacity.
For Large Systems is the autonomous AP still a lower cost alternative? No, Split MAC is lower cost for large systems.
What are the options for PoE? Switch with inline, Inline Power Patch Panel, Power Injector, Direct Power via Power Brick.
What is a Bridge Network? Connecting 2 wired LAN segments through wireless bridging.
What is a Bridge / Backhaul Network? Connecting buildings through wireless. P2P or Point to Multipoint.
Default Password on APs? Cisco (case sensitive)
Default IP on AP? 10.0.0.1 /27
Default SSID on AP? tsunami
Does PoE send data and power over the same pairs? Mode A = yes, Mode B = no.
Will plugging an Ethernet cable from a PoE interface on a PSE device into another interface on the same PSE cause damage? No. Have to ask for the power.
What is Wireless Propagation? Total of everything that happens to a wireless signal as it travels from source to destination.
What is Wavelength? Distance between 2 successive crests (peaks) of a wave pattern.
What is Attenuation? Lowering of the signal amplitude as it travels, by various means.
Does Wavelength affect Attenuation? Shorter = MORE, Longer = LESS
Which has longer wavelength, 2.4GHz or 5GHz? 2.4GHz has a longer wavelength. Lower frequency = longer wavelength.
What is Frequency? Number of RF signal cycles within a specified time interval. Measured in Hz.
What is Amplitude? Signal's strength or power. Bigger Peaks = Bigger Amplitude.
What is Transmit Amplitude? Amount of initial amplitude that leaves the radio transmitter. Cables and connectors attenuate the transmit amplitude, antenna will amplify.
What is Received Amplitude? The strength of the signal that the receiving antenna gets. Will always be smaller than the transmit amplitude.
What is Phase? Relationship between 2+ signals that share the same frequency. Can cause amplification, attenuation and nullification (null at 180).
Part of the power of the signal gets taken into the object which it is interacting with. Absorption
When a wave hits a smooth object the wave may bounce in another direction. Reflection
RF signal encounters some type of uneven surface and is reflected into multiple directions. Scattering
Bending of an RF signal as it passes through a medium causing the direction of the wave to change. Refraction
Bending and the spreading of an RF signal when it encounters an obstruction. Diffraction
Loss of signal strength caused by the natural spreading of the waves. Free Space Path Loss
Two or more paths of a signal arriving at a receiving antenna at basically the same time. Multipath
What are the effects of Multipath? Since waves will be out of phase it can cause up/down fade, complete nulling, and data corruption.
What is the purpose of infrastructure SSID mode on the ROOT AP? If you designate an SSID as the infrastructure SSID, infrastructure devices must associate to the access point using that SSID
Where do you configure Maximum Association? dot11 ssid
What is the purpose of infrastructure SSID mode on the Repeater / Hot Standby? Sets the ssid that will be used to either repeat or monitor. They will associate to the Root with this SSID.
What does the acronym IAPP stand for? Inter Access Point Protocol
Verify standby status: show iapp standby-status
Verify standby timers: show iapp standby-parm
What do you associate to with iapp standby command for the hot standby? Mac-address of the root radio interface.
What role do you set a hot standby to be? root access-point.
Do you use a straight-through or crossover cable to connect from wall to AP? Straight-through
What are the 4 main stages to configuring any AP? BVI, SSID, Wireless Radio, Sub-Interfaces
What causes human body to absorb RF signals? High water content.
What can cause Multipath to occur? Reflection, Scattering, Diffraction, and Refraction.
Do rain, snow, and hail affect wireless radio? No, they have no serious impact (direct) impact. Rain can physically impair an antenna or cause a surface to become more reflective.
Does wind have any affect on wireless communication? Yes, can cause antenna to change the aim, or possibly destroy the tower or mast.
How do you delete a configuration that may be stored on the AP? write erase
Advantages of wireless bridge: throughput many times faster than T1, cheaper to implement, easy to install
Will a Root Bridge communicate with another Root Bridge? No.
Will a Root Bridge communicate with a Non-root bridge? yes
Will a Non-Root bridge communicate with a Non-Root bridge? no...unless other non root device is communicating with a parent, so yes...maybe.
Distance of Point-to-Point Bridge? 40km (25 miles)
With a point to point bridge, is it considered 1 or 2 segments? It will be one segment.
How many bridges can be aggregated with Etherchannel? 3
For point to multipoint what type of antenna is typically used at the main site? Omni-directorional
For point to multipoint what type of antenna is typically used at remote sites? Directional
In point to multipoint configuration can the remote sites communicate with each other? Yes but not directly, they must go through the main site.
Why do wireless bridges that support distances over one mile have to violate the 802.11 standard? 802.11 sets a time limit for ACK, so the bridge products have a parameter that increases this timing.
In long distance bridging will Cisco bridges function with radios of other vendors? They might not!
What are some long range antenna types? Yagi - 11.7km, Solid Dish - 40km
What OS was running on the Cisco Aironet 350 bridges? VXWorks, it was a GUI
What is the recommended overlap for adjacent BSS cells? 10-15%
Do adjacent APs require the same SSID to support roaming? Yes
What is the recommended overlap for a wireless repeater? 50%, so that the repeater can communicate with the root AP
What is the maximum recommended amount of repeaters in a chain? No more than 2
With 2 APs of different vendors, can you provide redundancy and load balancing? Redundancy = yes, Load Balancing = no
Does a Hot-Standby provide redundancy or load balancing? Redundancy
What is a critical component to having multiple overlapping networks? They must be in different non interfering channels. 1,6, and 11 for 2.4GHz
What is the IEEE standard to support Roaming? No standard yet, Task Group F is working on it.
Which protocol do most vendors use to support roaming? IAPP - Inter-Access Point Protocol
Does the client associate or authenticate to the AP first? First = authenticate, Second = associate
How many APs can a radio associate to? 1
To support seamless roaming, is it necessary to have APs of the same vendor. Yes, or at least recommended.
Does the client or the AP initiate roaming? Client
Briefly describe roaming process: Move away from connected ap = signal strength down, neighboring ap = signal strength up. At some threshold the client will change associated AP.
What is the signal strength threshold? If the signal strength is below the threshold the client should search for a better AP.
What is the wait threshold? After associating to an AP the client must wait a set number of seconds before they can search for a better AP.
What is Proxy Mobile IP? Used to make sure the client keeps the same IP while roaming, creating a tunnel to the clients original network. Transparent to the client.
How do APs handle clients moving further away from them? They will shift to a slower data rate. This is called Data Rate Shifting or Multi-Rate Shifting.
What is World Mode? Transmit power is limited to the max level allowed by the regulatory agency of the country where it is being used.
What is the purpose of this command: encryption vlan 110 mode wep mandatory Enables WEP on VLAN 110
What is a RADIUS server used for? Authentication
What are some Network Security Perimeter Devices? Firewall, Intrusion Detection / Prevention System, URL Filter / Web Proxy, Spam filter
What methods are there for Wi-Fi security? Encrypt data, Encrypt medium, Environmental shielding, user education.
Are all wifi attacks meant to gain unauthorized access? Some are just to disrupt.
What is dumpster diving? Literally going through garbage to try to get passwords or anything to help break into a network.
Who is Kevin Mitnick? Used social engineering to gain access to many systems.
Are Help Desk employees target for social engineering? Yes, they often hold keys to accessing the wi-fi network.
Who are the targets of social engineering? Contractors, Help Desk, Employees, end users
What are the countermeasures to Social Engineering attacks? Education, Good Policies, shred-it boxes.
What is the principle of minimal access? Only give access to resources that are absolutely needed.
What type of attack is War Driving considered? Eavesdropping
What are some Network Discovery tools? NetStumbler, Kismet, Easy Wi-Fi Radar
What are some Packet Sniffing / Injection tools? Wireshark, AirPcap, OmniPeek, Javvin CAPSA, CommView, MS NetMon
What are some Eavesdropping Countermeasures? Shielding, Hidden SSID (not great), Disable mixed mode (5GHz + 2.4GHz together)
How is layer 2 DoS attack accomplished? De-auth the target through de-auth frames or excessive interference.
What can layer 2 DoS attack lead to? Hijacking. Having the target connect to a Rogue AP instead of the normal AP they used to be on.
What is the difference between layer 2 and 3 Hijacking? With layer 3 they will give the user an IP address as well through a Rogue DHCP server.
What is PNL? Preferred Network List. List of SSIDs that a device will try to associate. Makes for good rogue AP targets.
What is WIDS a countermeasure for? Wireless Intrusion Detection System can find and drown out Rogue APs. Hijacking countermeasure.
What is layer 1 DoS? RF Jamming, creates so much background noise that devices cannot communicate.
What are some common accidental layer 1 DoS devices? Microwave, Cordless phone.
What is a PS-Poll Flood? PS = Power Saving, AP caches data for STA to send in intervals, attacker spoofs MAC and sends PS-Poll to collect the data.
What is Association / Auth Flood? Association / Auth packets with random MAC IDs.
What are some DoS countermeasures? You can use spectrum analyzer to find where they are attacking from, not much else.
What is Management Interface Exploit? When attacker is associated to the same subnet as the management interface, they can attempt to guess password.
What are Management Interface Countermeasures? VLAN segmentation, strong passwords.
Should you use TKIP or AES with WPA? AES, TKIP has known vulnerabilities.
What weakness does LEAP have? ASLEAP, intercept the challenge and response and then brute force the password.
What weakness does PEAP and EAP-TTLS have? If proper certificate validation is not performed an attacker can terminate the TLS tunnel and gather plaintext authentication info. Hijacking / MITM.
What are Cracking Countermeasures? Complex key, WPA + AES, WPA2, Certain WPS, Proper PEAP + EAP-TTLS
What is good and bad with WPS? Wifi Protected Setup, push button = good, 8 digit pin = 11,000 posibilities instead of 10^8...bad
What happens when the lightweight AP cannot obtain an IP address from a DHCP server? Continuously resets. It requires DHCP to start up.
What is the default information of the controller? Role = Master, IP = 172.16.0.254, VLAN = 1, AP Group = Default
What is a PSK? Pre Shared Key, basically a password.
What is the difference between Enterprise and Personal WPA2? Personal = Key, Enterprise = 802.1X auth (RADIUS) + AES encryption
Other names for Autonomous APs? Standalone, Fat, Intelligent edge
Disadvantage of Autonomous AP? separately configured, unique settings, must physically visit to change settings, manual load balancing.
Which layer does management config occur on Autonomous APs? access layer
Which layer does management config occur on Controller? Core (possibly distribution or access tho, so like anywhere)
What functionality does the LWAP provide? Functionally just a radio card and an antenna, all intelligence is on the controller.
Can WLAN controller act as a switch? yes
Can WLAN Controller act as a router? Many can, using OSPF
How do most WLC communicate with their LWAPs? Encapsulate the 802.11 frame into an IP tunnel, creates a point-to-point link between the WLC and the LWAP
What standard is there for WLC to LWAP communication? No standard, proprietary protocols used to transfer config settings, update firmware and maintain keep-alive traffic. Generic Routing Encapsulation (GRE) is common.
How does the LWAP receive and send frames? Receive = 802.11, send = using 802.3 wired connection using IP-encapsulated tunnel
What gets set in the AP group profiles? Channel, transmit power, and supported data rates.
How many group profiles can an AP belong to? 1
What gets set in the WLAN profile? SSID, Security, VLANs, QoS
How many WLAN profiles can an AP belong to? Many
What are virtual WLANs? WLC can create them, each gets linked to a virtual BSSID (radio MAC), and SSID which is assigned to a specific VLAN.
What is captive portal used for? Authenticate guest access, very limited encryption.
How can WLC handle load balancing and redundancy? Supports VRRP (like HSRP), load balances between multiple LWAPs
What kind of security feature does WLC provide? Some have integrated WIDS
How does WLC handle RF spectrum management? Collects data from LWAPs which monitor their own channels as well as off-channels, the WLC can dynamically change channel or power settings based off info.
Aruba 3200 Controller Info: APs = 32, Users = 2048, ports = 4 x Gb
How does Aruba LWAP get image? From controller via FTP, config pushed via PAPI (how the controller talks to the AP)
How many GRE tunnels are created for LWAP / WLC communication? 1 per SSID and per Radio
What is WPA? Wi-Fi Protected Access, With TKIP = bad, with AES = good
What is TKIP? Temporal Key Integrity Protocol, used as a stop gap to fix broken WEP
What is WEP? Wired Equivalent Privacy. Very broken, not equivalent to wired at all.
What is AES? Advanced Encryption Standard, used with WPA optionally and WPA2 mandatory.
What is EAP? Extensible Authentication Protocol, LEAP = bad, PEAP + EAP-TTLS = good
Created by: Datheral