Friday, August 26, 2016
Friday, August 19, 2016
Sunday, March 27, 2016
Cisco CLI Analyzer 2.0 Released - IOS and NX-OS support added!
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Monday, March 14, 2016
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
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.
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
Tuesday, March 1, 2016
Networking Questions 2016 - Part2
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
― Brad Henry
Saturday, February 27, 2016
Networking Questions for 2016 - Part 1
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
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.
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
― Peter Drucker
Tuesday, February 16, 2016
1Tbps: researchers break broadband speed record
Download entire Games of Thrones season in one second.
Researchers from the University College London (UCL) have
discovered the fastest ever data rate in digital information,
suggesting one day a movie could be downloaded within one second.
The researchers from UCL’s Optical Networks Group had achieved a rate
of 1.125 Tb/s as part of research on the capacity limits of optical
transmission systems. The research was designed to address the growing
demand for fast data rates.
Monday, October 5, 2015
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.
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.
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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