wlan interview questions and answers
The following are the top wlan interview questions and answers asked for networking and wireless network engineer job interviews
1. You have been asked to setup a server based authentication for wlan authentication. Name a free server which you would use for this setup.
Freeradius can be used for the purpose. Freeradius can be setup and installed on Linux platforms.
2. In EAP-TLS based wlan authentication, how are the session keys generated for wlan encryption.
The session keys are generated using TLS. The client and the server generates the session key using the client and server certificate installed respectively on each of them.
3. What is the size of the fixed key used by WEP.
4. What type of authentication does WPA use
WPA uses the 4 way handshake for authentication and key generation.
5. What type of authentication takes place between a wireless client and access point initially when a 802.1x infrastructure is used.
Initially it is open system authentication which is performed. After it is successful, the authentication between the client and the server happens with a combination of username / password and digital certificates.
6. At which layer of the OSI model does an access point come.
An access point comes at the data link layer of the OSI model.
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7.What is the terminology used to identify the name of the access point
SSID is the terminology used for naming an access point.
8.An access point is setup on a network. The access point has dhcp service enabled on it. The network also has a DHCP server. Should the DHCP server on the access point disabled ?
Yes. The dhcp server on the access point should be disabled. If not, there would be DHCP conflicts on the network.
9. How many devices can connect to an access point
This would depend on the type of the access point and the model.
10. How many SSID can be configured on a dual band access point
Each of the bands can be configured with one SSID each. So two SSID can be configured.
11. Which security protocol does WEP use for encrypting the packets
WEP uses RC4 for encryption.
12. Can wireless router affect internet speed
Yes. Each router, based on the standard supports different speeds. For example, a 1200 Mbps router would provide more speed than a traditional router which supports 54 Mbps. This would indirectly affect the effective speed provided to the client.
13. An access point is connected to a fast ethernet switch which supports 100 Mbps. Can the access point deliver 100 Mbps speed to the wlan clients.
No. The wireless clients would only be able to support the speed which is supported by the access point and not the switch. If the access point supports a speed which is greater than 100 Mbps, then the wlan clients would be able to achieve the speed.
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14. What type of frames are used by WLAN clients to authenticate with the access point.
There are two types of frames which are authentication request which is sent by the client to the access point and the authentication response which is sent by the access point to the client. Following the authentication phase, the access point and the client exchange association request and response packets in a similar fashion following which the client connects to the access point successfully.
15. Two laptops attempt to connect to an access point using WPA encryption as shown in the below diagram. Would the key used by the access point be the same or different for each of the laptops.
The key used by the access point would be the same. It is a pre-shared key which is shared with the wireless clients which require access to the access point.
16. Can a wireless router be converted into an access point.
Yes. A wireless router can work as an access point. The WAN interface of the wireless router should not be used in this case.
17. A user connects to the an access point using open system authentication and without any encryption. He then access a website on the internet. Can a hacker view the contents of the traffic sent from the user to the website.
If the website is accessed using https, it would not be possible since https is encrypted. But if the website is accessed using http, then it would be possible since the information is send in clear text.
17. A user connects to the an access point using open system authentication and without any encryption. He then access a FTP server on the internet. Can a hacker view the contents of the FTP traffic sent from the user to the FTP server.
Yes. FTP is an insecure protocol. Since encryption is not used on the Wifi channel, all traffic is sent in clear text. This makes it possible to view the contents of the packet.