Networking questions part 1

I'm going to try to submit questions at least once a month this year (hopefully more often)

Here's the first batch, enjoy....

1. What layer of the OSI Reference Model sends and receives bits and specifies the electrical, mechanical, procedural and functional requirements for maintaining a physical link between end systems?

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

2. What Cisco IOS keyboard shortcut recalls the oldest command in the command history, beginning with the most recent command?

A) Ctrl+B
B) Ctrl+E
C) Ctrl+U
D) Ctrl+N
E) Ctrl+P

3. 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

4. When would an interface need a clock rate?

A) When the interface is DTE
B) When the interface is DCE

5, 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

6. 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

7. What is port 21 used for?

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

8. What does the term "Logical address" refer to?
A) MAC address
B) Physical address
C) IP address
D) Link-layer address

9. What is the maximum number of hosts you can assign to a class C network if it is not subnetted?

A) 1024
B) 254
C) 32
D) 512
E) 65025

10. A router has two Fast Ethernet interfaces and needs to connect to four VLANs in the local network. How can you accomplish this task, using the fewest physical interfaces and without decreasing network performance?

A. Use a hub to connect the four VLANS with a Fast Ethernet interface on the router.
B. Add a second router to handle the VLAN traffic.
C. Add two more Fast Ethernet interfaces.
D. Implement a router-on-a-stick configuration.

1. Correct Answer E

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

2. Correct Answer E

Keyboard Shortcut Action

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.

3. Correct Answer A

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

4. Correct Answer B

Cisco routers are DTEs by default (Data Terminal Equipment). The DCE (Data Circuit-Terminating Equipment) at the other end of the connection must supply a clock rate to the DTE.

5. Correct 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.

6. 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

7. Correct Answer B

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.

8. Correct Answer C

A Logical address is normally a 32-bit IP address assigned to each host in an IPv4 network.

A Physical address is a unique 48-bit flat address normally burned into the ROM of the NIC card, and therefore cannot be changed. It is divided into 24-bit vendor code and 24-bit serial address.

9. Correct Answer B

For class C the number of bits for host address portion is 8. So 2^8 -2 = 256-2 = 254 hosts.

10. Correct Answer D

A router on a stick allows you to use sub-interfaces to create multiple logical networks on a
single physical interface.

How did you go? If you disagree with any of my answers or find errors, please leave a comment. More coming soon..stay tuned :-)

I remind myself every morning: Nothing I say this day will teach me anything. So if I'm going to learn, I must do it by listening.
Larry King

Networking Questions 2016 Part 5

Here are some more very random networking questions based around the CCNA type of exam head scratchers... :-)

1. What type of NAT allows you to map multiple unregistered IP addresses to a single registered IP address?

A) Static NAT
B) Dynamic NAT
C) Overloading (Port Address Translation)

2. Each port on a switch is a separate broadcast domain?

A) True
B) False

3. Inter-Switch Link and IEEE 802.1Q are types of...

A) Spanning Tree Protocol
B) Trunking method
C) Ethernet
D) Routing protocol

4. What statement is not correct when talking about a shared-medium Ethernet LAN?

A) The data frame broadcast delivery nature of Ethernet can have a negative affect on performance
B) Adding repeaters and hubs to an Ethernet network can increase latency
C) Ethernet is a best-effort delivery service
D) Collisions are caused by CSMA/CD on an Ethernet network

5. What TCP/IP layer are TCP and UDP protocols associated with?

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

6. What IOS command would you issue in privileged-mode to change the Cisco router configuration stored on TFTP?

A) config t
B) config mem
C) config net
D) config tftp









1. Answer: C

PAT (Port Address Translation) allows you to map multiple unregistered IP addresses to a single registered IP address.

2. Answer: B

Switches create separate collision domains but a single broadcast domain.

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

3. Answer: B

Both Inter-Switch Link and IEEE 802.1Q are types of VLAN identification.  Inter-Switch Link (ISL) is a Cisco proprietary protocol whereas IEEE 802.1Q is a standard method of frame tagging.
4. Answer: D (did you get the "not"?)

Carrier Sense Multiple Access / Collision Detection (CSMA/CD) is a set of rules determining how network devices should respond when two devices try to use the shared medium simultaneously.

http://en.wikipedia.org/wiki/Carrier_sense_multiple_access_with_collision_detection
5. Answer: B

TCP and UDP protocols are associated with the Transport layer of the TCP/IP model, which is sometimes referred to as the "host-to-host transport layer".

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

Internet protocol suite examples:
Application layer
BGP · DHCP · DNS · FTP · HTTP · IMAP · LDAP · MGCP · NNTP · NTP · POP · ONC/RPC · RTP · RTSP · RIP · SIP · SMTP · SNMP · SSH · Telnet · TLS/SSL · XMPP ·
Transport layer
TCP · UDP · DCCP · SCTP · RSVP 
Internet layer
IP  (IPv4 · IPv6) · ICMP · ICMPv6 · ECN · IGMP · IPsec  
Link layer
ARP · NDP · Tunnels  (L2TP · PPP · MAC  (Ethernet · DSL · ISDN · FDDI ·

6. Answer: C

To change the router configuration stored on TFTP you use configure network (config net)


More random question 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

IPV4 Subnetting Tips

It always takes a bit to get your head around subnetting for the first time, and even more to answer the exam questions they give as they often are designed to trick you.

For random IPV4 subnetting questions to hone your skills, I suggest you bookmark:

http://www.subnettingquestions.com/

Memorizing the tables help immensely,  although at first appearance they appear daunting.

/24	8	255.255.255.0	256 = 28	Large LAN
/25	7	255.255.255.128	128 = 27	Large LAN
/26	6	255.255.255.192	64 = 26	Small LAN
/27	5	255.255.255.224	32 = 25	Small LAN
/28	4	255.255.255.240	16 = 24	Small LAN
/29	3	255.255.255.248	8 = 23	Smallest multi-host network
/30	2	255.255.255.252	4 = 22	"Glue network" (point to point links)
/31	1	255.255.255.254	2 = 21	Point to point links (RFC 3021)
/32	0	255.255.255.255	1 = 20	Host route

TIPS:

Remember the binary number doubles for each bit.  2, 4, 8, 16, 32, 64, 128, 256 etc

Also remember 8, 16, 24, 32 for the 8 bit block sizes. 

To find the block size, find the first octet that is not 255, then subtract it from 256... eg subnet mask of 255.255.255.224 ...256 - 224 = block size of 32 

Subtract 2 from the block size to get the number of hosts eg 32 - 2 = 30 host IP.
(network and broadcast addresses cannot be used for user IP)

For the slash format, eg /27 subtract 27 from 32 to give a remainder of 5
Then if we count up 5 times doubling, 2, 4, 8, 16, 32 we get to the same block size of 32.

We also see that 224 is equal to 3 subnet bits taken from the octet ( 11100000) in a C class subnet, this will equal 8 subnets (allowing for subnet zero) 1, 2, 4 = 7+1 = 8 subnets.


Some providers have questions relating to old routing kit that did not allow the use of the all "1" subnet or all the "0" subnet (known as 'subnet zero').On all new Cisco routers, the number of subnets is calculated using the formula of 2^n by default. However, for legacy routers network engineers use 2^n - 2 to comply with the almost obsolete RFC 1878 standard. 

Some text books and courses that relate to old routing equipment also refer to the old formula as do some Microsoft Learning courses. If you're planning to take a non-Cisco exam that involves subnetting you should make sure you understand the 'subnet zero' concept' and check what is considered the default correct formula by your examining board

Once you get the patterns 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, etc and the masks 255, 254, 252, 248, 240, 224, 192, 128 burnt in it will become way easier :-)

Networking Questions 2016 - Part 3

The next installment of Six more random networking questions for your enjoyment :-)


1.  When STP is converging no data can move through the switched network.

A) True
B) False

2. What should be carried out within the Cisco hierarchy at the distribution layer?

A) ACL
B) Security and network policies
C) VLANs
D) WAN access
E) All of the above

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

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

4. If applied to an interface what would this ACL do?

Router(config)#access-list 25 deny 172.32.10.0 0.0.0.255
Router(config)#access-list 25 permit any

A) Deny traffic from the 172.32.10.0 network
B) Deny SMTP traffic from the 172.32.10.0 network
C) Deny traffic from the host 172.32.10.0
D) Deny SMTP traffic from the host 172.32.10.0
E) Allow all traffic

5.  Your network features a combination of Cisco, 3COM and Netgear switches. You have been tasked to set up VLANS on your switched network.

What trunking method should you use?

A) Inter-Switch Link
B) IEEE 802.1Q
C) You can't create VLANs by combining switches from different vend

6. When you connect to a remote router "out-of-band", via what port would you connect with?

A) Console port
B) Auxiliary port
C) Ethernet port
D) Serial port

Free Cisco labs for CCNA, CCNP and CCIE students!
Presented by René Molenaar - CCIE #41726

1. Answer A 

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

2. Answer E

Distribution layer (Workgroup layer): Ensures packets are properly routed between subnets and VLANs using LAN-based routers and Layer 3 switches. In the Distribution layer are:

• Firewalls, security, network policies, and network address translation (NAT) are configured.
• Routing between workgroups and VLANs is accomplished.
• Access lists, packet filtering, and queuing are implemented.

3. Answer A

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
4. Answer A

This standard ACL denys traffic from the 172.32.10.0 network and allows everything else.

5. Answer B 

ISL is a Cisco proprietary frame tagging method and therefore only works with Cisco switches.
IEEE 802.1Q is the networking standard that supports virtual LANs (VLANs) on an Ethernet network.

6. Answer B

When a router is out-of-band (out of the network) you would connect remotely via a modem attached to the auxiliary port.

Check back regularly, more questions every week 

(if time permits).

   “I seldom end up where I wanted to go, but almost always end up where I need to be.”

― Douglas Adams

Networking Questions 2016 - Part2

Another half a dozen random networking posers to get you thinking, have fun :-)


1. Lets start simple, What is port 23 used for?

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

2. 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

3. In a local broadcast all bits set to 1 are received by all hosts on local and remote broadcast domains?

A) True
B) False

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

A) True
B) False

5. What is the correct sequence of Spanning Tree states?

A) Blocking, Listening, Learning, Forwarding, Disabled
B) Disabled, Blocking, Listening, Learning, Forwarding
C) Learning, Listening, Forwarding, Disabled, Blocking
D) Listening, Learning, Forwarding, Blocking, Disabled

6. What do asymmetric switches require?

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






1.  Answer C

The Telnet is a TCP/IP protocol which defines a text based communications session between a client and a host using TCP port number 23.

2. 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.

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

3. Answer B

Routers don't forward broadcasts so local broadcasts will stay on the broadcast domain from which they originated.

 4. 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.

 5.  Answer A

STP switch port states:

Blocking
Listening
Learning
Forwarding
Disabled

A switch does not enter any of these port states immediately except the blocking state. When the Spanning Tree Protocol (STP) is enabled, every switch in the network starts in the blocking state and later changes to the listening and learning states.

6. Answer A

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

Progressively harder ?? stay tuned for more  

- thank you.

“A good teacher can inspire hope, ignite the imagination, and instill a love of learning.”

― Brad Henry

Networking Questions for 2016 - Part 1

A new set of half dozen networking questions to get you thinking.  


I'm going to expand into SDN, Security and NVF questions over the next few months to keep things current :-) Enjoy.

1. 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

2. What is the dotted decimal format of the loop back address?

A) 192.168.0.0
B) 127.0.0.1
C) 192.0.0.1
D) 227.0.0.1

3. What is the reserved address space for a Class C 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 

4.  Where is the start-up configuration file held in a router?

A) NVRAM
B) RAM
C) Routing table
D) ROM

 5. 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

 6. What are the three layers of the Cisco hierarchical model?

A) Core layer, Network layer, Access layer
B) Core layer, Distribution layer, Access layer
C) Physical layer, Network layer, Transport layer
D) Media Layer, Transport layer, Application layer
 

Free Cisco labs for CCNA, CCNP and CCIE students!
Presented by René Molenaar - CCIE #41726

1. Answer E 

Trick question to start the series :-). IP provides no form of error correction/acknowledgements.

2.  Answer B 

127.0.0.1 is a special reserved IP address which is used as a host's loopback address. Messages sent to loopback address do not get placed on the LAN, instead they are re-routed by the host's own network adapter back to the receiving end of the TCP/IP stack.

3. Answer D 

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

 
 4. Answer A

The IOS software in Cisco devices looks for a valid configuration file stored in NVRAM. which is called as startup-config. If a startup-config file is not in NVRAM, the router will start the setup-mode configuration upon boot up.

5.  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.

 6. Answer B 

Core layer: Considered the backbone of the network (high-end switches, high-speed cables). Concerned only with speed and reliable delivery of data. No packet filtering happens here.

Distribution layer (Workgroup layer): Ensures packets are properly routed between subnets and VLANs using LAN-based routers and Layer 3 switches.

Access layer (Desktop layer): Deals with connecting workstations to the network with switches and hubs.

How did you go?  Stay tuned for more in the coming weeks and months  :-)

 

 “Follow effective action with quiet reflection. From the quiet reflection will come even more effective action.”
― Peter Drucker

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



=======================================
A social trading platform at the top of its class. State-of-the-art software, excellent customer support and a trading platform that is not only reliable, but also enjoyable make eToro a top choice when looking for a Forex broker.   

  ===========================================

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 :-)

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

 =========================================================

AZOD.com.au is a mobile phone and electronics company that is focused on delivering high quality products to Australian customers at affordable prices - Mobile phone, tablets, computers etc. We are constantly updating our product offering in line with advancements in technology and changes in consumer demands. Our primary focus is providing the best customer service in Australia. We provide hassle free returns or replacements on any items that are received faulty. We truly hope you have an excellent shopping experience with us and we will endeavor to answer all your questions and provide the best service we possibly can before, during and after your purchase from us. Thank you from all the staff here for supporting us and we hope you recommend your friends and family to come back and buy again. Keep an eye out for our weekly specials!

    =========================================================

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 :-)

Random Cisco based networking questions - CCNA - Part 7

Here is another set of network based questions and answers to get the grey matter ticking.. have fun :-)




1. STP will work on which of the following devices?

A) Hub
B) Router
C) Switch
D) Repeater

2. What command would you use copy the current configuration to a TFTP host?

A) copy flash tftp
B) copy run tftp
C) copy tftp flash
D) copy nvram tftp

3. You are designing a subnet mask for the 172.22.0.0 network. You want 11 subnets with up to 3300 hosts on each subnet. What subnet mask should you use?

4. What would you do if you're locked out of a router because you forgot the password?

A) Call Cisco support
B) Issue the show run command to view the password
C) Perform the password recovery procedure
D) Press the reset button on the back of the router
5. What does Serial 0 is up, line protocol is down indicate?

A) Keepalive or framing issue
B) Carrier detect is not present
C) The interface is shutdown
D) The interface is functioning correctly

6. With full-duplex Ethernet no collisions can occur.

A) True
B) False

7. How would you disable CDP on a Cisco router or switch?

A) disable cdp
B) shutdown cdp
C) no cdp enable
D) no cdp run
E) You cannot disable CDP

8. What type of ACL is this and what is it performing?

Router(config)#access-list 150 deny tcp any host 172.32.14.2 eq 25

A) Standard ACL, deny all SMTP traffic to host 172.32.14.2
B) Standard ACL, deny all Telnet traffic to host 172.32.14.2
C) Extended ACL, deny all SMTP traffic to host 172.32.14.2
D) Extended ACL, deny all Telnet traffic to host 172.32.14.2
E) Named ACL, deny all SMTP traffic to host 172.32.14.2
9. What does the trace response N mean?

A) Network unreachable
B) Not forwarded due to ACL restriction
C) Protocol unreachable
D) Port could not be reached

10. 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













1. Correct Answer C 

The Spanning Tree Protocol (STP) is a Data Link layer protocol that ensures a loop-free topology for a bridged LAN. 

Therefore STP will only operate on layer 2 devices such as bridges and switches.

2. Correct Answer B

The current configuration is known as the running-configuration (or 'run' for short). The copy command is in the format "copy " therefore copy from run to the tftp host (i.e. copy run tftp).

3. Correct Answer 255.255.240.0

4. Correct Answer C

To reset the password on a router interrupt the boot sequence, change the configuration register, reboot, copy startup-config to running-config and change the password.  Then reset the configuration register.

5. Correct Answer A

The various states of an interface:

Serial0 is up, line protocol is up - The interface is functioning correctly.

Serial0 is down, line protocol is down - This message usually represents a physical interface problem. The cable may be disconnected. This can also occur if this interface is connected to another router whose interface has been shutdown.

Serial0 is up, line protocol is down - The Physical layer connectivity is not the issue. The line protocol being down is either a clocking issue (keepalives) or a mismatch of the frame types being used on connected devices.

Serial0 is administratively down, line protocol is down - The interface has been manually shutdown using the shutdown command.

6. Correct Answer A

http://en.wikipedia.org/wiki/Full-duplex_Ethernet

7. Correct Answer D

To turn off CDP use the no cdp run command from the global configuration mode.

8. Correct Answer C

Router(config)#access-list 150 deny tcp any host 172.32.14.2 eq 25

Port 25 is SMTP. This extended ACL denies traffic from any source to host 172.32.14.2.

9. Correct Answer A

Cisco Trace Command Response Codes

Response Meaning
 * Timed out
 !H router received packet but did not forward it
 N network unreachable
 P protocol unreachable
 U port unreachable

10. 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.

Stay tuned more to come - have a great day.

I remind myself every morning: Nothing I say this day will teach me anything. 

So if I'm going to learn, I must do it by listening.
Larry King

Random Cisco based networking questions - CCNA - Part 6

 Here's another half a dozen random networking questions to get the grey matter ticking :-)



1. 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

2. Where would you place standard access lists?

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

3. Frame tagging is used to identify...

A) The intended recipient of a frame
B) The IP address of the frame
C) The source of the frame
D) The VLAN ID of the frame
E) The trunking method

4. When each network segment uses a different subnet mask this is referred to as...

A) Classful routing
B) Classless routing

5. A CIDR value of /12 equates to what subnet mask?

A) 255.0.0.0
B) 255.128.0.0
C) 255.192.0.0
D) 255.224.0.0
E) 255.240.0.0

6. 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

1.  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.

2. Answer A

Standard access lists only filter based on source address so they have to be placed as close to the destination as possible.

3. Answer D

Frame tagging is used to tags frames on trunked links to identify what VLAN they belong to.

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

4. Answer B

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

5. Answer E

http://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing#Assignment_of_CIDR_blocks

6. Answer C

It is a good practice to backup your existing system image to the TFTP server using the copy flash tftp command.  I personally use Pumpkin or Solarwinds TFTP servers, but there are may other types around.

 Stay tuned for more updates, and let me know if you find these useful or any errors 

Please share around if you find these questions of value.

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