Monday, September 7, 2015

Random Cisco based networking questions - CCNA - Part 9

More network based questions and answers, part nine of the 2015 series, complete with wiki reference links for further reading :-)




1.  What TCP/IP layer are Telnet, FTP, TFTP and SMTP protocols associated with?

A) Application
B) Host-to-Host / Transport
C) Internet
D) Network Access


2. What is not a main switch function?

A) Address learning
B) Frame forwarding
C) Packet forwarding
D) Loop avoidance


3. What layer of the OSI model segments and reassembles data from upper-layer applications and brings them together in the same data stream?

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


4. VLAN trunk protocol is responsible for?

A) Tracking and monitoring VLANS
B) Consistent VLAN configuration
C) Trunking VLANs across mixed networks
D) Reporting New VLANs
E) All of the above

5. If you are trunking between non-Cisco switches what frame tagging standard should you adopt?

A) 802.1q
B) ISL
C) 802.3q
D) VTP


6. If your switch uses shared memory buffering, what would happen if a packet could not be delivered because of a busy destination port?

A) It would delay transmission of all packets in memory
B) It would be sent to the destination port anyway
C) It would wait in a queue while all other packets in memory are transmitted
D) It would drop the packet after an allocated time


7.What is the equivalent of the TCP/IP Network Access layer in the OSI Reference layer?

A) Network
B) Data Link
C) Data Link and Physical
D) Physical
E) Transport


8. What is the Spanning Tree forward delay?

A) The time that is spent in the Listening and Learning states
B) 50 seconds
C) Time taken for a switch to go from Listening to Forwarding
D) Time taken for a switch to go from Blocking to Forwarding




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1. Answer: A

http://en.wikipedia.org/wiki/Internet_Protocol_Suite


2.  Answer: C 

Switches are layer 2 devices and do not look at layer 3 packets.

3. Answer: C

http://en.wikipedia.org/wiki/Transport_Layer

4. Answer: E

VLAN Trunking Protocol (VTP) is a Cisco proprietary protocol that manages the addition, deletion, and renaming of Virtual Local Area Networks (VLAN) on a network.

http://en.wikipedia.org/wiki/VLAN_Trunking_Protocol


5. Answer: A

ISL is a Cisco proprietary VLAN tagging protocol and therefore if you have a multi-vendor switch network you will need to choose the IEEE 802.1q standard instead of ISL.


6. Answer: C

The area of memory where the switch stores the data is called the memory buffer.
The memory buffer can use two methods for forwarding frames:
 

port-based memory buffering
shared memory buffering

In port-based memory buffering frames are stored in queues that are linked to specific incoming ports.

Shared memory buffering deposits all frames into a common memory buffer which all the ports on the switch share.


 7. Answer: C 

The link layer has the networking scope of the local network connection to which a host is attached. It is the lowest component layer of the Internet protocols, as TCP/IP is designed to be hardware independent. As a result, TCP/IP may be implemented on top of virtually any hardware networking technology.

http://en.wikipedia.org/wiki/TCP/IP_model#OSI_and_TCP.2FIP_layering_differences


8. Answer: A

Forward delay — The time that is spent in the listening and learning state, 15 sec by default, but you can tune the time to be between 4 and 30 sec.





Stay tuned for more coming soon :-)




Friday, September 4, 2015

Malware types explained.

The amount of cyber attacks is on the rise across the globe,  Here is a quick refresher on what the different types are.

Spyware.

 This malicious software keeps an eye on your computer use without your knowledge. It collects a variety of data, depending on its design. Some forms of this malware are actually legal, often bundled with free software; it monitors your web browsing habits, uploading the data to advertising servers.

Ransomware.


This new type of malware holds your computer or files hostage and demands a payment. Some forms may simply display a pop-up demanding money before you can continue using your computer. More harmful versions encrypt your files, rendering you helpless unless you’ve got backup.

The Trojan, or Trojan Horse. 


This type of malware disguises itself as a legitimate file. When you download and run the program, the malware runs in the background, allowing third parties to access your computer. This malware is often used to monitor activity on your computer, or to link your computer to a botnet.

The Virus. 


This malware copies itself by infecting other files. It can do many different things — watch in the background and steal your passwords, display advertisements, or just crash your computer — but its key characteristic is how it spreads: by infecting programs on your computer. When you run the program on another computer, the virus will infect programs on that computer, and so on.

The Worm.


 This malware spreads in a unique way. Rather than infecting files and relying on human activity to propagate, it spreads over computer networks of its own accord. It can do any number of harmful things once it infects a computer.

Malvertising. 


This term describes the use of online advertising to spread malware.


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Tuesday, September 1, 2015

Random Cisco based networking questions - CCNA - Part 8

Here are another set of Random networking questions to ponder, good start for September :-)

I saw Bloke with a bumper sticker saying: "I am a veterinary surgeon, therefore I drive like an animal." Suddenly I realised how many gynecologists and proctologists there are on the roads.:-)




1. What is Cisco's default NAT table entry timeout (translation timeout)?

A: 1 hour
B: 12 hours
C: 24 hours
D: 36 hours
E: 48 hours


2. 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


3. What is port 20 used for?

A: FTP data
B: FTP program
C: Telnet
D: SMTP
E: TFTP


4. Extended ACL allow you to filter Application layer traffic.

A: True
B: False


5. What command would you use to erase the startup config of a router?

A: erase nvram
B: erase flash
C: delete startup
D: erase startup
E: delete run


6. What is the reserved address space for a Class B network?

A) 10.0.0.0 - 10.255.255.255
B) 20.0.0.0 - 20.255.255.255
C) 172.16.0.0 - 172.31.255.255
D) 192.168.0.0 - 192.168.255.255
E) 208.168.0.0 - 208.168.255.255


7. What is responsible for ensuring a router is functional and the interfaces are present on booting?

A) Bootstrap
B) POST
C) ROM monitor
D) NVRAM
E) Configuration register


8. Store and forward switching method is best described by which of the following?

A) The entire frame is received before forwarding is commenced
B) Forwards frame after receiving destination address
C) Filters out collision packets by waiting for the first 64 bytes of data



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1. Answer: C

When an entry is placed into the NAT table a timer begins, the duration of this timer is called the translation timeout, defaulted to 24 hours on Cisco routers.


2. Answer: C

http://en.wikipedia.org/wiki/Transport_Layer

3. Answer: A

File Transfer Protocol (FTP) is a network protocol used to copy files from one host to another over a TCP/IP-based network.
A client makes a TCP connection to the server's port 21. This connection remains open for the duration of the session called the control connection, with a second connection, called the data connection, opened by the server from its port 20 to a client port required to transfer file data.


4. Answer: A

To filter Application layer traffic using extended ACLs, first specify TCP, then the port number of the Application layer protocol.

5. Answer: D

To erase the startup configuration use the following command:

Router#erase startup-config
or
Router#erase startup


6. Answer: C 

http://en.wikipedia.org/wiki/Private_network#Private_IPv4_address_spaces

7.  Answer: B

POST (Power-on-self-test) stored in ROM performs a basic router health-check on booting.

8. Answer: A

Store and forward switching method is known as store and forward because the switch will store the incoming data frame in its internal buffer, then when the complete frame has been received the switch will then run a Cyclic Redundancy Check (CRC) against the frame. If the CRC passes, the switch will then look up the destination MAC Address in its MAC filter table to forward it on to its destination.



How did you go?  stay tuned for more coming soon :-)