A new series of Cisco base networking questions for 2014 - part2

A set of questions for those interested in IT / networking / certification or just generally curious  - Enjoy.

(This time with some IPv4 questions thrown into the mix :-)

The secret of life is not to do what you
like but to like what you do.
By: Anonymous

1. What will be the IP address of the second subnet given the following?

172.16.0.0 255.255.224.0 (Assume ip subnet-zero is enabled)

A) 172.16.0.0
B) 172.16.8.0
C) 172.16.16.0
D) 172.16.32.0
E) 172.16.64.0

2. What is the maximum number of subnets and hosts per subnet achievable from the network 172.22.0.0 255.255.255.224?

A) 2048 subnets and 30 hosts
B) 256-224=32 ip per subnet - 30 hosts
C) 256/32=8 subnets per 4th octet
D) 256 x 8 = 2048 total subnets for B class address


3. What are the 3 ways of assigning a switched port to VLANs?

A) Switch-centric, Port-centric, Dynamic VLANs
B) Port-centric, Static VLANs, Dynamic VLANs
C) Interface-based, Static VLANs, Dynamic VLANs

4. What is the default time BPDUs are sent and received by switches?

A) 2 seconds
B) 10 seconds
C) 30 seconds
D) 60 seconds

5. What does Router(config)# no access-list 1 command achieve?

A) Removes Access List 1
B) Disables ACL on interface 1
C) Nothing, this is not a Cisco command









1. Correct Answer: D 

The subnet block size is 256 - 224 = 32
The first subnet will be subnet zero 172.16.0.0
The second subnet will be 172.16.32.0

2. Correct Answer: A

2048 subnets and 30 hosts

3. Correct Answer: B

Three ways of assigning a switched port to VLANs:

Port-Centric - All nodes connected to ports in the same VLAN are assigned to the same VLAN ID.
Static VLANs - Statically assign ports to a VLAN.
Dynamic VLANs - Ports that can automatically determine their VLAN assignments based on MAC addresses.

4. Correct Answer: A 

The Spanning Tree Protocol (STP) is a network protocol that ensures a loop-free topology for any bridged Ethernet local area network. The basic function of STP is to prevent bridge loops and the broadcast radiation that results from them. Spanning tree also allows a network design to include spare (redundant) links to provide automatic backup paths if an active link fails, without the danger of bridge loops, or the need for manual enabling/disabling of these backup links.

The bridges have to determine the root bridge and compute the port roles (root, designated, or blocked) with only the information that they have. To ensure that each bridge has enough information, the bridges use special data frames called Bridge Protocol Data Units (BPDUs) to exchange information about bridge IDs and root path costs.

A bridge sends a BPDU frame using the unique MAC address of the port itself as a source address, and a destination address of the STP multicast address 01:80:C2:00:00:00.

There are two types of BPDUs in the original STP specification (The Rapid Spanning Tree (RSTP) extension uses a specific RSTP BPDU.[4]):

Configuration BPDU (CBPDU), used for Spanning Tree computation
Topology Change Notification (TCN) BPDU, used to announce changes in the network topology
BPDUs are exchanged regularly (every 2 seconds by default) and enable switches to keep track of network changes and to start and stop forwarding at ports as required.

5. Correct Answer: A

"No" is generally used in front of Cisco config lines to remove them from configuration, in this case No Removes Access List 1

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A new series of Cisco base networking questions for 2014 - part1

Here are a number of random questions based on the Cisco certifications, but they relate to IT and networking in general as well. See how you go and check last years series for more!

(Some of these are a little tricky, just like the cert exams :-)

Action may not always bring happiness...
but there is no happiness without action.
By: Benjamin Disraeli

1. What is true about the MAC address?

A) Used to identify networks
B) Defined at the Network layer
C) Unique for every networked device in the world
D) Identical to the IP address

2. Bridges cannot provide congestive feedback information to end nodes?

A) True
B) False

3. What do asymmetric switches require?

A) memory buffers
B) extra ports
C) statically assigned ports only
D) high speed CAM

4. The Cisco Spanning Tree protocol is compatible with IEEE 802.1d?

A) True
B) False

5. What is the administrative distance of EIGRP?

A) 110
B) 1
C) 120
D) 90
E) 100

6. What IOS command would disable CDP on a routers interface?

A) no cdp enable
B) disable cdp
C) no cdp
D) no cdp run

7. Bridges forward layer 2 broadcasts, but switches don't.

A) True
B) False

8. Router>     What mode are you in when you see this prompt?

A) user exec mode
B) privileged mode
C) global configuration mode
D) interface configuration mode
E) routing protocol configuration

9. What layer of the OSI model is responsible for multiplexing upper-layer applications, establishing sessions and tearing down virtual circuits?

A) Presentation
B) Session
C) Transport
D) Network
E) Data Link

10. What is port 53 used for?

A) FTP data
B) FTP program
C) Telnet
D) DNS
E) TFTP

/center>

Answers to the above questions..

1. Correct Answer: C

MAC addresses are assigned by the manufacturer of a network interface card (NIC) and are stored in its hardware. A MAC address contains the manufacturer's identification number.
The MAC address may also be referred to as the burned-in address, hardware address, Ethernet address or physical address and is part of the Data Link layer, specifically the Media Access Control sub-layer of the Data Link layer.

2. Correct Answer: A

Flow Control and Congestive Feedback are functions of the Network layer. Bridges operate at the Data Link layer so these responsibilities fall to the end devices in a bridged environment.

3. Correct Answer: A

With ability for support of high bandwidth ports Asymmetric Switches require more Buffer memory for storing & forwarding of packets for fast processing.

4. Correct Answer: B

The original Spanning-Tree protocol was created by Digital Equipment Corporation (DEC) which is now part of Compaq. The IEEE created its own version called IEEE 802.1d which is not compatible with the original version. Cisco enhanced the original 802.1d specification with features such as Uplink Fast, Backbone Fast, and Port Fast to speed up the convergence time of a bridged network. However these new features are proprietary, and can only be configured on Cisco switches.

5. Correct Answer: D

Administrative distance is used by Cisco routers to select the best path when there are two or more different routes to the same destination from two different routing protocols. Administrative distance defines the reliability of a routing protocol. EIGRP has an administrative distance of 90.

6. Correct Answer: A

You can disable CDP on an interface which supports CDP with the no cdp enable command.

7. Correct Answer: B

Both switches and bridges forward layer 2 broadcasts.

8. Correct Answer: A

Here is a summary of Cisco IOS router command prompts:

Router> - User EXEC mode
Router# - Privileged EXEC mode
Router(config)# - Global configuration mode
Router(config-if)# - Interface level configuration mode
Router(config-router)# - Routing engine level within configuration mode
Router(config-line)# - Line level (vty, tty, async) within configuration mode

9. Correct Answer: C

The Transport layer is responsible for multiplexing upper-layer applications (ports), establishing sessions and tearing down virtual circuits.

10. Correct Answer: D

DNS uses commonly known port 53

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Owning your online presence - food for though.

Most of us know to secure our home networks, and to be wise in choosing when to connect to wireless networks when we’re out and about.  But did you know your device can be broadcasting your position even when it is not connected to a wireless network?


All WiFi-capable devices broadcast a unique ID called a media access control (MAC) address, when they're looking for networks, and so long as WiFi is enabled they are always looking for networks.  This means that if you walk around carrying a mobile device with WiFi enabled, then you are broadcasting your own unique radio beacon and it's easy to track your movements.

This GPS and Location-based information can be useful for the following:

•More accurate directions when using maps and directions.
•Customized information from shopping apps (showing nearest locations, deals in your area, etc.).
•Safety and peace of mind from “Find my Friends” (iOS) or “Guardian” (Windows) apps.  Apps like these can enable families to be aware of each other’s locations.  Guardian enables users to call for help through an 'SOS' alert button and also connect to security agencies, police and hospitals easily in times of crisis.  

This is not a comprehensive list, however it does show these features offer wonderful benefits.  But you want to make sure you are in control of the information you are broadcasting to the cyber world.

Is your smartphone broadcasting your movements when you shop?

Some retailers are taking advantage of the signal sent by WiFi-enabled devices. You might see a sign in a shopping center that reads:  “To provide a better shopping experience for our customers we anonymously survey the movement of mobile phones to help show us how the centre is used. No personal data is recorded at any time.”

This raises some security concerns such as claims the collected data would be de-identified and de-personalized, but “anonymous” data can still provide a lot of information and similar to other cookies and tracking methods, retailers want to use location information to produce personal profiles and targeted advertising.  But if retailers can use this information, so can phishers and social engineers.
This movement tracking is even speading to your car, with BMW developing similar technology which will allow businesses to market their products through the German car maker’s built-in satellite navigation system.
The easiest way to defeat the anonymous tracking -- simply turn off WiFi and Bluetooth on your mobile device when away from home.

Another tracking method expanding rapidly is Google’s Location History Browser, which gives a minute-by-minute map of your life.

Location History allows Google to store a history of your location data from all devices where you are logged into your Google Account and have enabled Location Reporting.  So if you have a device that uses a Google-driven operating system (e.g. an Android phone or tablet), there’s a good chance you had to answer a prompt about location history during device set-up.  And if you opted-in to this tracking, Google might have a pretty comprehensive history of where you’ve been.

This long-term tracking of location data can give deep insight into your habits and patterns.  On one hand, this can be eerie or even creepy.  But it can also be kind of fun and nifty to review.

To get around this, Google allows you to manage your privacy in two ways:  either by clearing your history, or by opting out of the service altogether.  Learn how here:  Manage Location in Google Settings

In Summary: Some tips to own your Online Presence

•When you’re not at home, consider turning off WiFi and Bluetooth.  This will both conserve your device’s battery life and also protect you from continually broadcasting your location.  Turn it on again when you want to connect to a wireless network.

•Review the privacy settings on your devices.  Be intentional about the apps you allow to access your location.  Consider turning permissions off when you are not actively using an app.

•Periodically clear your history.  This certainly applies to location history, but it applies to other kinds of history too -- this site offers practical tips for managing brower history and other private data