Random Cisco based networking questions - CCNA - Part 5

Another half a dozen random networking questions for 2015 with a more routing protocol focus this time, 

enjoy :-).

1. Triggered updates (in a routing protocol) are used to speed the convergence process?

A) True
B) False

2. What class of routing protocol is EIGRP?

A) Link state
B) Distance vector
C) Hybrid

3. What is the administrative distance of OSPF?

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

4. 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

5. What is required for VTP to communicate VLAN information between switches?

A) VTP domain must be identical on all switches
B) One switch needs to be a VTP server
C) A router is required
D) Both A and B are correct
E) None of the above

6. What is the structure of the MAC address?

A) 32 bit network ID + 32 bit host ID
B) 14 bit vendor code + 6 bit serial number
C) 24 bit vendor code + 24 bit serial number
D) Network + Host

Searching for what type of nic card you have in your PC? The easiest way is with the MAC address ( not the kind shown below :-)

A great link you should bookmark for Vendor/Ethernet/Bluetooth MAC Address Lookup and Search at MACFIND.  This allows you to match your MAC address to its vendor or a vendor to a MAC - I find it very useful :-).

http://www.coffer.com/mac_find/

1.  Answer A

A triggered update is sent immediately in response to a change in the network (e.g. A link going down). The router detecting the change immediately sends an update message to its adjacent routers, which then generate their own triggered updates. This process continues until the network converges. Triggered updates occurs independently from the regular routing updates and are intended to speed the convergence process.

2. Answer C

EIGRP is a hybrid routing protocol which uses a combination of distance vector and link state methods to determine the best path. EIGRP is considered an advanced distance vector protocol because EIGRP sends out only incremental updates.

3. Answer A

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.

Routing Protocol	Administrative distance
Directly connected interface	0
Static route out an interface	1
Static route to next-hop address	1
DMNR - Dynamic Mobile Network Routing	3
EIGRP summary route	5
External BGP	20
Internal EIGRP	90
IGRP	100
OSPF	110
IS-IS	115
Routing Information Protocol (RIP)	120
Exterior Gateway Protocol (EGP)	140
On Demand Routing (ODR)	160
External EIGRP	170
Internal BGP	200
Floating Static Route (ex. DHCP-learned)	254
Unknown	255

(Note : An AD of 255 will cause a router to dump this route from its table)

4. Answer D

To erase the startup configuration use the following command:

Router#erase startup-config, or
Router#erase startup

5. Answer D

VTP requires the following to communicate VLAN information between switches.  The VTP domain must be identical on all switches and one switch needs to be a VTP server.

6. Answer C

MAC Addresses are 48 bits long and consist of a 24 bit vendor code and a 24 bit serial number.

More coming, please leave comments if you find any errors or want to debate an answer :-)

Random Cisco based networking questions - CCNA - Part 4

Welcome to part 4 of the random networking questions (Cisco based) series.  This set has a few extra spanning tree questions with detailed explanations, have fun :-)


1. What is the default time Bridge Protocol Data Units (BPDUs)  are sent and received by switches?

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

2. What does the following statement do?

Switch(config-if)#spanning-tree portfast disable

A) Disables spanning-tree on the switch port
B) Disable spanning tree on the switch
C) Changes the spanning-tree switch to portfast mode

3. What determines network addresses (IP) when data link addresses (MAC) are known?

A) Ping
B) ICMP
C) ARP
D) RARP

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

A) True
B) False

5. What type of switch port can belong to multiple VLANS?

A) Access port
B) Trunk port
C) Voice access port
D) No port can belong to multiple VLANs

6.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

Speaking of IP, I sometimes use a simple little site that gives you your own IP and other internet connectivity details   - IP Chicken - handy link  :-)

1. Answer A

http://en.wikipedia.org/wiki/Spanning_tree_protocol#Bridge_Protocol_Data_Units_.28BPDUs.29

Bridge Protocol Data Units (BPDUs) frames are sent out as multicast messages regularly at multicast destination MAC address 01:80:c2:00:00:00. When Bridge Protocol Data Units (BPDUs) are received, the Switch uses a mathematical formula called the Spanning Tree Algorithm (STA) to know when there is a Layer 2 Switch loop in network and determines which of the redundant ports needs to be shut down.

Three types of Bridge Protocol Data Units (BPDUs) are Configuration BPDU (CBPDU), Topology Change Notification (TCN) BPDU and Topology Change Notification Acknowledgment (TCA).

2.  Answer A

The time Spanning Tree Protocol (STP) takes to transition ports over to the Forwarding state can cause problems. PortFast is a Cisco network function which can be configured to resolve this problem by disabling STP from the switchport, thus making it come up quicker.

3. Answer D

Reverse Address Resolution Protocol (RARP) is used by a host computer to request its IPv4 address from an administrative host (DHCP server), it provides the server with its hardware address (MAC address).

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


NOTE: Dynamic Host Configuration Protocol (DHCP) is a client/server protocol that automatically provides an Internet Protocol (IP) host with its IP address and other related configuration information such as the subnet mask and default gateway.

4.  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. Answer B

Ethernet interfaces can be configured either as access ports or trunk ports. Trunks carry the traffic of multiple VLANs over a single link and allow you to extend VLANs across the network.

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

6. 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

How did you go? I find a quick review of the questions and answers helps cement the basics and refresh the memory  - I hope these help, stay tuned for more...

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

Random Cisco based networking questions - CCNA - Part 3

Welcome to part 3 of the random networking questions (Cisco based) series.

Ready to get the brain tickin? Lets go!

1. What Cisco IOS enhanced editing command end the configuration mode and returns to EXEC?

A) Ctrl+Z
B) Ctrl+W
C) Ctrl+F
D) Esc+F
E) Tab

2, Which devices operate at the Data Link layer?

A) Switch
B) Bridge
C) Repeater
D) Router
E) Both A and B

3. Triggered updates are used to speed the convergence process?

A) True
B) False

4. Which switching mode is the most likely to forward frames containing errors?

A) FIFO
B) Modified Cut-Through
C) Store-and-Forward
D) Cut-Through
E) Fragment-Free

5. What is the function of asymmetric switching?

A) To prioritise bandwidth to nodes that need it
B) To prevent bottlenecks on the port a server is connected to
C) To allow RAS clients to connect to the network

6. PPP can be used over what types of serial connections?

A) Synchronous
B) Asynchronous
C) Both
D) Neither










1. Answer A

Keyboard Shortcut Actions (I've published this before but thought it worthy to remind :-)

Up Arrow Displays your previous commands.  (command history)
TAB Key Completes a partially typed CLI commands.
CTRL+Z Takes you back to Privileged EXEC Mode.

CTRL+A Places the cursor at the beginning of a line.
CTRL+E Places the cursor at the end of a line.
CTRL+R Redisplays the current command line.
CTRL+W Erases a word (behind the cursor).
CTRL+U Erases an entire line.

2. Answer E

Bridges and switches filter network traffic based on the MAC address (hardware address) and are Data Link layer devices.

A Repeater does not apply any filtering and is therefore a Physical Layer device.

Routers forward packets based on logical network addresses are are Network Layer devices.

3. Answer A

A triggered update is sent immediately in response to a change in the network (e.g. A link going down). The router detecting the change immediately sends an update message to its adjacent routers, which then generate their own triggered updates. This process continues until the network converges. Triggered updates occurs independently from the regular routing updates and are intended to speed the convergence process.

4. Answer D

Cut-Through switching is also referred to as Fast Forward.

When in cut-through mode the switch waits for the destination MAC Address to be received. Once the MAC Address is known the switch refers to its MAC filter table to determine which port the frame should be forwarded out. The switch forwards the frame even before the entire frame has arrived.

Frames with and without errors are forwarded in cut-through switching, leaving the error detection of the frame to the intended recipient.

5. Answer B

An asymmetric switch provides switched connections between ports of different bandwidths.
Asymmetric switching is optimized for client-server traffic where multiple clients simultaneously communicate with a server, requiring more bandwidth dedicated to the server port to prevent a bottleneck at that port.

6. Answer C

Point-to-Point Protocol (PPP) can be used over ISDN (synchronous) and dial-up (asynchronous) connections.

All over the place that time - stay tuned for the next batch - coming soon:-)

  “Employ your time in improving yourself by other men's writings, so that you shall gain easily what others have labored hard for.”
 Socrates 

Random Cisco based networking questions - CCNA - Part 2

Part 2 in the series of random networking questions for 2015, to keep you current or stimulate thought..

 1. Where would you place more specific tests in your access list?

A) At the top
B) At the bottom
C) Placement doesn't matter


2. Routers are what by default?

A) DTE devices
B) DCE devices

3. Which WAN protocol is capable of carrying video, Circuit Switched Data And Telephone Services using normal phone network?

A) Frame Relay
B) ISDN
C) PPP
D) ISL

4. What protocol range would you use for IP in ACLs?

A) 1-99
B) 800-899
C) 200-299
D) 1000-1099

5. What IP address will test the internal loopback of a node?

A) 127.0.0.1
B) 255.255.255.255
C) 0.0.0.0
D) 126.0.0.1
E) 127.0.0.0

6. When each network segment uses a different subnet mask this is refered to as...

A) Classful routing
B) Classless routing












1. Answer A

Always organise your access lists so the more specific tests are at the top.

2. Answer A

A router is configured as a DTE by default. If a clock rate speed is not specified, the router is configured as a DTE. If a clock rate speed is specified, the router is configured as a DCE.

DTE = Data Terminal Equipment
DCE = Data Communications Equipment

 3. Answer B

ISDN (Integrated Services Digital Network) is a set of standards for simultaneous digital communications (voice, video, data) over the traditional circuits of the public switched telephone network.

4. Answer A

Standard Cisco IOS Help output
Router#configure terminal
Router(config)#access-list ?
 <1-99>  IP standard access list
 <100-199> IP extended access list
 <1100-1199> Extended 48-bit MAC address access list
 <1300-1999> IP standard access list (expanded range)
 <200-299> Protocol type-code access list
 <2000-2699> IP extended access list (expanded range)
 <700-799> 48-bit MAC address access list
 rate-limit Simple rate-limit specific access list

5.  Answer A

127.0.0.1 is the loopback address in IP, it is a test mechanism for network adapters. Messages sent to 127.0.0.1 do not get delivered to the network. The NIC intercepts all loopback messages and returns them to the sending application.

6. Answer B

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

More coming, please leave comments if you find any errors or want to debate an answer :-)

"Whatever you are, be a good one."

Abraham Lincoln

Random Cisco based networking questions - CCNA - Part 1

The first half a dozen of random networking questions to get you thinking in 2015 :-)

Enjoy,,

1. Where would you place extended access lists?

A) As close to the destination as possible
B) As close to the source as possible

2. Bridges can only have one spanning tree instance, while switches can have many.

A) True
B) False

3. What would happen if you put the following ACL on an interface?

access-list 1 deny 172.168.0.1
access-list 1 deny 192.5.2.1

A) All traffic from 172.168.0.1 and 192.5.2.1 would be denied
B) All traffic would be denied
C) Nothing
D) These are not Cisco IOS ACL commands

4. Which layer of the OSI model is concerned with Media Access Control addresses?

A) Layer 1
B) Datalink layer
C) Application Layer
D) Session Layer
E) Transport Layer

5. What do the IOS commands below achieve?

Router(config)#access-list 5 permit 172.5.15.2
Router(config)#line vty 0 4
Router(config-line)#access-class 5 in

A) Create an extended ACL to only permit host 172.5.15.2 to connect to VTY
B) Create a standard ACL to only permit host 172.5.15.2 to connect to VTY
C) Create an extended ACL to only permit hosts on the network 172.5.15.2 to connect to VTY
D) Create a standard ACL to only permit hosts on the network 172.5.15.2 to connect to VTY
6. 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









1. Answer B 

Extended access lists are much more granular than standard ACLs, you can block specific ports or protocols.

To avoid unnecessary traffic on your network place them as close to the source as possible.

2. Answer A (true)

Bridges are software based and can only have one spanning-tree instance per bridge, while switches are hardware based and can have many.

3. Answer B

People forget the not shown the automatic deny any any on the tail end of any access list :-)

4. Answer B

Media Access Control is a sublayer of the Data Link Layer specified within the OSI model. It provides addressing and channel access control.  The hardware that implements the MAC is referred to as a Media Access Controller.

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

5. Answer B

Router(config)#access-list 5 permit 172.5.15.2
Router(config)#line vty 0 4
Router(config-line)#access-class 5 in

This standard access list permits only the host 172.5.15.2 to connect to your VTY telnet line.

6. 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.

How did you do?? stay tuned more coming or check out the previous posts :-)

"If you want success, then don't rely on other people to do what YOU can do!" 

Sasha Azevedo

Data retention for eternity.

The next breed of solid state drives maybe ???

Researchers at a Zurich university have succeeded in storing and retrieving digital information in DNA segments, the molecules that encode genetic information, a breakthrough that could lengthen the lifespan of information storage by millions of years.

In a paper published by Angewandte Chemie, the team of researchers from Eidgenössische Technische Hochschule described how they managed to translate the 1291 Federal Charter of Switzerland and Archimedes' The Methods of Mechanical Theorums, a total of 83 kilobytes of information, into 4991 segments of DNA.

Researchers in the United States were able to encode a 5.27 megabyte book with images into DNA two years ago

Read more: http://www.itnews.com.au/News/400620,researchers-make-dna-data-storage-breakthrough.aspx#ixzz3S4edCjXP

A new round of Network Q&A will be coming soon - stay tuned....

Ian

HAPPY NEW YEAR

HAVE A HAPPY NEW YEAR 

MAY YOU HAVE A HAPPY AND PROSPEROUS 2015

Ian B  - Life is An Adventure.

SECURITY TIPS KEEPING FINANCIAL DATA UNDER LOCK AND KEYBOARD

As the holiday season is upon us, a timely reminder regarding internet security is in order, as the scammers will be on the increase over the Christmas period.

•  Don’t provide your PIN or Internet banking login or password to anyone

•  Delete spam and scam e-mail – DON’T open it

•  Keep your anti-virus and firewall software up-to-date

•  Always logon to Internet banking by typing in your bank’s full web address. Never give your confidential banking details to anyone

•  Don’t ever use public computers for Internet banking, for example, Internet cafes, libraries or hotels

•  Guard your identity information carefully and only provide to trusted people and entities – such as your date of birth, current address, driver’s license number and passport details

•  Be cautious about unsolicited offers or opportunities offering you the chance of making easy money

•  Be wary of offers from people or companies overseas as it makes it harder to check if they are bona-fide

•  Take steps to verify any company which makes you a job offer, for example, address, phone number, e-mail address and website. Check if it is a registered company

•  Always guard your personal information and be suspicious if someone asks for a host of personal details soon after contact

•  Be wary of a person asking for financial assistance – be aware if you send money by wire transfer these funds cannot be recovered by banks

•  Be cautious of someone asking for details of your financial status – do not provide the information

May you have a happy and safe Christmas season 

see you in the New Year - Ian B 

More neworking questions in the 2014 series - Final?

Time to stretch the grey matter with some more Cisco based networking questions...with some subnetting thrown in to add to the annoyance  :-)



1. If a switch receives a multicast frame, what does it do with it?

A) Forwards it out every port
B) Sends it back to the originator asking for a destination address
C) Drops the frame

2. 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

(Might need a pencil for the next 2 :-)

3. What valid host range is the IP address 172.25.78.33/27 part of?

4. Which subnet does host 172.26.147.25 255.255.255.224 belong to?

5. IGRP advertises routes to interior, system and exterior routes

A) True
B) False

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 default administrative distance of a static route?

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

8. Trunk links are used to communicate between...

A) Two switches
B) A switch and router
C) A switch and server
D) A switch and PC
E) A, B and C are correct






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1. Correct Answer A 

Internally multicast is treated as broadcast. So the Switch, will send it to all port except from which it recieve. Same way it will treat broadcast also.

2. Correct Answer C

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

3. 172.25.78.33 through to 172.25.78.62

4. 172.26.147.0

5. Correct Answer A

IGRP advertises three types of routes:

Interior routes are routes between subnets in the network attached to a router interface.
System routes are routes to networks within an autonomous system.
Exterior routes are routes to networks outside the autonomous system.

6. Correct 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. Correct Answer A

The default administrative distance for a static route is 1.

8. Correct Answer E

A trunk link is a point-to-point link between two switches, a switch and router or a switch and server which carries multiple VLAN traffic.

Not sure if there will be more questions before Christmas, however I plan new sets for 2015 so come back and we'll have some more lernin... :-)  

Have a good Christmas.

Networking Questions and Answers

Here's another set of Cisco based networking questions to mull over - enjoy!

1. How would you copy the IOS to a TFTP server?

A) Router(config)#copy ram tftp
B) Router(config)#copy tftp flash
C) Router#copy flash tftp
D) Router#copy tftp flash
E) None of the above 

2. What determines network addresses when data link addresses are known?

A) Ping
B) ICMP
C) ARP
D) RARP

3. What process is used to check whether packets have been received when using IP?

A) Acknowledgments
B) CRC
C) Windowing
D) Flow control
E) None

4. What is the maximum number of subnets given the following?

192.168.10.0
255.255.255.192
(Assume ip subnet-zero is enabled)

A) 4
B) 8
C) 16
D) 32
E) 64

5. Ip subnet-zero is enabled on all your routers.
How many bits must you borrow to create 16 subnets?

A) 1
B) 2
C) 3
D) 4
E) 5

6. What is the maximum size of an Ethernet packet when the frames have ISL tagging?(Include the size of headers and CRC)

A) 64 bytes
B) 1500 bytes
C) 1518 bytes
D) 1522 bytes
E) 1548 bytes

7. Which of the following are Routed protocols?

A) IP, IPX, ICMP
B) IP, IPX, Appletalk
C) RIP, IGRP, EIGRP
D) Both A and B are correct

8. What is the encapsulation type of Transport Layer?

A) Segments
B) Packets
C) Frames
D) Bits

9. 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

10. What is the numerical value of the Bridge Priority held by Catalyst switches?

A) 32500
B) 32768
C) 100
D) 1024
E) 32700






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1. Correct Answer C

It is a good practice to backup your existing system image to the TFTP server using the copy flash tftp command.

2. Correct Answer D

Reverse Address Resolution Protocol (RARP) is used by a host computer to request its IPv4 address from an administrative host, it provides the administratiev host with its hardware address (MAC address).

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

3. Correct Answer E

Trick question. IP provides no form of error correction/acknowledgements.

4. Correct Answer A

192.168.10.0 is a class C address.  The subnet mask 255.255.255.192 implies 2 bits are borrowed.
22 = 4 subnets

5. Correct Answer D

24 = 16

6. Correct Answer E

Cisco's proprietary VLAN tagging (ISL) has a maximum frame size of 1548 bytes.
IEEE 802.1q VLAN tagging has a maximum frame size of 1522 bytes.

7. Correct Answer D

Routed Protocols are layer 3 Network Layer protocols. They include Internet Protocol (IP), Internetwork Packet Exchange (IPX) and Apple's AppleTalk. Routed or routable protocols allow for internetwork communication by assigning network and host identities to packets, without routed protocols network communication would be restricted to the local segment.

Internet Control Message Protocol (ICMP) is a TCP/IP protocol that works at the network layer and is used to report errors and deliver messages. ICMP is also considered a routed protocol.

8. Correct Answer A 

The Transport layer protocol data unit (PDU) is the 'Segment'

9. Correct Answer A

If you wish to remove an access-list, you use the no access-list (list #) command.

10. Correct Answer B 

The Bridge Priority is the numerical value held by switches. All Catalyst switches have a default priority of 32768. To determine the root bridge you combine the priority of each bridge with its MAC. If two switches have the same priority value the lowest MAC address becomes the root bridge.

 How did you go - Interesting huh - More coming stay tuned... Have a great day!!!