Layer 2 - Data Link Layer - Transmission Technologies

7 Written Questions

1. - operates in different frequency range - 5 GHZ.
   - less prone to interference.
   - greater speeds.
   - not as widely used.
2. transmission of frames to all machines on the broadcast network.
3. - chatty.
   - no dedicated path required.
4. - straight out of the box, no security configured at all.
   - WAPs are usually configured to broadcast their presence.
   - each wireless network node and access point needs the same SSID.
   - could choose not to broadcast SSID.
   - Also could implement MAC filtering.
5. - used for router-to-router traffic, and home user to ISP traffic.
   - handle error detection.
   - allows IP addresses to be negotiated.
   - so used in dial up it will set-up the connection with ISP and negotiate an IP address.
   - replaced SLIP in many uses.
6. - developed before 802.11a.
   - data throughput of up to 11Mbps.
   - most widely used standard; as a result the frequency is crowded; might run into interference from other wireless devices.
   - networks secured through use of WPA and WEP.
   - 2.4 ghz
7. - associated with point-to-point networks.
   - point to point transmission with one sender and one receiver.

6 Multiple Choice Questions

1. transform raw transmission facility into a line that appears free of undetected errors to the network layer.
   Accomplishes this by having the sender break up the input into frames, and transmit them sequentially. If the service is reliable, the receiver confirms the correct receipt of each frame.
   1. Circuit switching
   2. Point to point protocol (PPP)
   3. Packet-switching
   4. Main task of the data link layer
2. transmission of frames to a subset of the machines on the broadcast network.
   1. switches
   2. Broadcast
   3. Unicast
   4. Multicast
3. data link layer protocol described by the 802.11 standard.
   - uses RC4 often reuses IV.
   - many installations use the same shared key for all users, so each user can read each others traffic.
   - vulnerable to a number of known attacks.
   1. WEP
   2. WPA2
   3. SSID
   4. ARP
4. - available in a range of mobile devices.
   - operates in both ad-hoc mode and infrastructure mode.
   - by default security is disabled but does have three security modes, ranging from full data encryption to integrity control.
   - only authenticates devices, not users.
   - vulnerable to buffer over flow.
   1. Blue tooth
   2. Broadcast
   3. Unicast
   4. bridges
5. allows an anonymous message to be displayed on victims device.
   1. Blue bug attack (bluetooth)
   2. Blue tooth
   3. Blue jacking (bluetooth)
   4. Packet-switching
6. data link layer does not understand IP addresses.
   ARP sends out request, who owns IP address? this is used to build table of MAC 48 bit addresses to IP addresses.
   - defined in RFC 826.
   - vulnerable to ARP poisening ( adding bogus entries to ARP cache).
   1. WPA2
   2. SSID
   3. WEP
   4. ARP

6 True/False Questions

1. bridges → connects two or more LANs.
   When a frame arrives, software in the bridge extracts the frame header and looks it up in a table to see where to send the frame.
   - different line cards for different technologies, Ethernet, FDDI etc.
   - each line has its own collision domain.

   True        False

2. Circuit switching → - chatty.
   - no dedicated path required.

   True        False

3. Blue bug attack (bluetooth) → allows an anonymous message to be displayed on victims device.

   True        False

4. switches → connects two or more LANs.
   When a frame arrives, software in the bridge extracts the frame header and looks it up in a table to see where to send the frame.
   - different line cards for different technologies, Ethernet, FDDI etc.
   - each line has its own collision domain.

   True        False

5. 802.11g → - developed before 802.11a.
   - data throughput of up to 11Mbps.
   - most widely used standard; as a result the frequency is crowded; might run into interference from other wireless devices.
   - networks secured through use of WPA and WEP.
   - 2.4 ghz

   True        False

6. WPA2 → - based on EAP framework; negotiate authentication method at startup.
   - 802.1X standard.
   - uses AES

   True        False