Tuesday, December 10, 2013

Keep your Networks and Data Safe.


Home Wireless Devices: 


Most wireless access points are ready-to-go right out of the box, but from a security perspective, they are wide open and insecure. This means that anyone driving (or walking) by your house or living in close proximity to your house can instantly connect to your wireless access point. Without proper security configurations enabled, your neighbors can even connect to the Internet through your network at no cost to them and could possibly access files on your home systems which reside on your PC or network.


We urge you to follow and apply the guidelines below where possible.


Protect Your Personal Information:


•Remember that everyone can view data in the airspace. Protect it appropriately by encrypting the data by using Wi-Fi Protected Access (WPA and preferably WPA2).
•Install personal firewalls and Anti-Malware software on all devices and have the most up-to-date signature files installed. You should also have the latest security patches (such as Microsoft Windows updates and Adobe Reader updates) installed on your system.
•Change the administration password on the Access Point to something other than the default one assigned by the manufacturer.
•The Service Set ID (SSID) is the name of your wireless network. For example, a Linksys router most commonly has a default SSID of "linksys." You should change your SSID from the manufacturer default, but not to something that is easily guessable.  Avoid using mailing addresses, street names, or your last name.  This can give away too much information about your physical location or identity. Suggestions might include: "homenet8273" or "h563."

Keep a Clean Machine:

•Make sure you’re using the latest firmware update for your specific Access Point / Wireless Router. Not only will you benefit from hardware bug fixes, you may also gain improved security features as well. Firmware updates are usually freely available from the manufacturer’s website and include instructions on how to perform the upgrade.
•Using Internet Security all-in-one tools are also recommended as they usually have Host Intrusion Prevention tools which are not dependent on signature files and are more behavior based.

Connect with Care:

•For the more technically savvy, you can filter, by Media Access Control (MAC) address, what devices/computers can connect and obtain an IP address from your wireless Access Point. There is a table where you can enter the MAC address from each device/computer on your network that you want to allow to communicate.
•Disable "remote administration" for the Access Point (usually the default setting). This is different from local administration, which is always enabled. Remote administration can potentially allow untrusted users on the Internet to connect to your wireless access point and administer it.



LearnSecurityOnline.com is a highly interactive online security training experience. We do this by utilizing simulators, security games, challenge servers, and hacking competitions to give you both the technical knowledge and hands-on experience required to be a competent IT & IT Security Professional all in a safe and legal environment.

Thursday, October 24, 2013

NASA sets space communications speed record



NASA said its Lunar Laser Communications Demonstration (LLCD) aboard the Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft reached 622 megabit per second download speeds by using a pulsed focused light beam, covering a distance of some 385,000 kilometres.


NASA sets space communications speed record - Telco/ISP - Technology - News - iTnews.com.au

Wednesday, September 25, 2013

Cisco based Networking Questions part xiii

Your time is limited, so don’t waste it living someone else’s life.
 –Steve Jobs

Random Cisco based networking questions and answers to help with accreditation or just for fun :-)

1. 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


2. What Cisco IOS command executes the configuration stored in NVRAM.

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


3. How would you disable an interface (Cisco command)?

A) Router(config-if)#shutdown
B) Router(config-if)#disconnect
C) Router(config-if)#disable
D) Router(config-if)#close
E) Router(config-if)#stop


4. 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


5, Given the IP address 192.168.10.0 
What subnet mask should you use to create 16 subnets?
(Assume ip subnet-zero is enabled)

A) 255.255.255.240
B) 255.255.240.0
C) 255.240.0.0
D) 255.255.255.248
E) 255.255.248.0


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


Bonus Question

IGRP advertises routes to interior, system and exterior routes

A) True
B) False






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1. Correct 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.


2. Correct Answer: B
config mem executes configuration commands stored in NVRAM by copying startup-config to the running-config


3. Correct Answer: A
The interface command shutdown disables an interface.


4. 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


5. Correct Answer: A
This is a class C IP address, so octets 1-3 cannot be used for subnetting.
24 = 16 subnets, which means we need to borrow 4 bits.
The fourth octet value should therefore be 240.


6. Correct 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


Bonus Question. 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.


How did you go? let me know,,

Saturday, September 21, 2013

Cisco Based Networking Questions part xii

Strive not to be a success, but rather to be of value. 
–Albert Einstein.

More Random Cisco Based networking Questions for you to ponder.

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

A) True
B) False


2. Which protocol is used to determine the IP address if the MAC address is already known?

A) ARP
B) RARP
C) IP
D) IPX
E) TCP


3. What is the invalid timer set to by default when you have a router running the Interior Gateway Routing Protocol?

A) 3 times the update period
B) 270 seconds
C) 3 times the update period + 10 seconds
D) Answer A and B
E) 7 times the update period


4. The startup-config (Cisco) is found in the ...

A) FLASH
B) DRAM
C) NVRAM
D) ROM


5. What component of a router holds the routing tables and the software that allows the router to function?

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


6. Which switching mode has the highest degree of error checking?

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





1. Correct Answer: B
Routers don't forward broadcasts so local broadcasts will stay on the broadcast domain from which they originated.


2. Correct Answer: B
Reverse Address Resolution Protocol (RARP) is a networking protocol used by a host computer to request its IP address from an administrative host, when it knows its MAC address.


3. Correct Answer: D
IGRP sends its routing table to its neighbors every 90 seconds. IGRP uses an invalid timer to mark a route as invalid after 270 seconds (three times the update timer). IGRP uses a flush timer to remove a route from the routing table (default flush timer is 630 seconds, seven times the update period).


4. Correct Answer: C
The startup configuration is stored in NVRAM


5. Correct Answer: D
The running-config is stored in RAM and allows the router to function.


6. Correct Answer: D
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.


More to come - stay tuned...

Monday, July 22, 2013

Cisco Based Networking questions - part xi

Another set of 6 random IT questions to active your grey matter :-)

1. Hosts on one VLAN that want to communicate with another VLAN need to go through a router.

A) True
B) False


2. Triggered updates are used to speed the network convergence process?

A) True
B) False


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 administrative distance of RIP?

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


5. What Cisco IOS command executes the configuration stored in NVRAM.

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


6. Where would you place extended access lists?

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




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1. Correct Answer: A
VLANs act as if they are different networks.  So communication between VLANs require routers.


2. Correct 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.


3. Correct Answer: E
Trick question. IP provides NO form of error correction/acknowledgements.


4. Correct Answer: C
Here in the question the A is administrative distance 110 for OSPF, B is 1 for Static Route, D is 90 for Internal EIGRP, E is 100 for IGRP so the last C is 120 for RIP.


5. Correct Answer: B
config mem executes configuration commands stored in NVRAM by copying startup-config to the running-config


6. Correct 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.






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Monday, July 15, 2013

Cisco based exam questions - part x

Part 10 of random Cisco CCNA based questions to stimulate some thought or just refresh - enjoy


1. 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


2. HDLC is ISO standard WAN protocol which means you don't need Cisco routers at both ends of a WAN connection, a router from any vendor that supports HDLC will work.

A) True
B) False


3. 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


4. What is the IEEE standard describing VLANs called?

A) IEEE VLAN
B) 802.3
C) 802.1q
D) 802.11b
E) 802.3q


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

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


6. What do asymmetric switches require?

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





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1. Correct Answer: D
To erase the startup configuration use the following command:

Router#erase startup-config
or
Router#erase startup


2. Correct Answer: B
Even though HDLC is an ISO standard, each vendor has their own implementations of HDLC.


3. Correct 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.


4. Correct Answer: C
The IEEE 802.1Q standard specifies a standard method for inserting virtual LAN (VLAN) membership tags into Ethernet frames.


5, Correct Answer: C
Point-to-Point Protocol (PPP) can be used over ISDN (synchronous) and dial-up (asynchronous) connections.


6. 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. 



How did you go? couple of tricky ones there huh :-)
More coming, stay tuned!



amaysim - One pure SIM

Friday, July 12, 2013

Subnets and subnet masks


One of the most complex tasks TCP/IP has to perform is to determine whether or not a given IP address exists on the same subnet. The task isn’t really that complicated once you understand how TCP/IP uses its IP address and subnet mask, here's a very basic rundown.

An IP address looks something like this: 192.168.10.52. IP addresses always contain four numbers from 0–255, separated by periods. A portion of the IP address is called the network ID and acts as a unique identifier for a particular subnet.

The rest of the IP address is called the host ID and identifies a particular computer or network device on that subnet uniquely. How can you tell which part of the IP address is which? By using the subnet mask. A subnet mask looks a lot like an IP address, with four groups of numbers: 255.255.255.0. Remember, computers are binary machines that can understand only in zeros and ones. For the subnet mask to make sense, you have to translate it and the IP address into binary.
 
TIP: You can switch the Windows Calculator into Scientific view, which enables you to convert numbers from decimal to binary.


Convert all the four groups (octets) of numbers into binary code. For example, an IP address of 192.168.10.41 and a subnet mask of 255.255.255.0 look like this in binary:


Address or Mask 1st octet 2nd octet 3rd octet 4th octet

192.168.10.41 11000000 10101000 00001010 00101001

255.255.255.0 11111111 11111111 11111111 00000000



Everyplace you see a “1” in the subnet mask corresponds to the portion of the IP address that is the network ID. Everyplace you see a “0” in the subnet mask corresponds

to the portion of the IP address that is the host ID. Here, the network ID is 192.168.10, and the host ID is 41.TCP/IP treats everything with an IP address that starts with 192.168.10 as if it were on the same subnet. Any IP address that starts with something other than 192.168.10 is treated as if it existed on another subnet. 



 
Basic TCP/IP Services

A number of the protocols in the TCP/IP suite are considered core protocols, which means they are usually present on any network that uses TCP/IP. The core protocols provide basic services that no network can do without. These services include

_ Data transmission. Is handled by more than one protocol: the User Datagram Protocol (UDP) and the Transport Control Protocol (TCP). Computers use UDP when they need to send a small packet of data and don’t care if the remote computer actually receives the data. Computers use TCP when loads of data needs to be transmitted because TCP allows the remote computer to reply, confirming its receipt of the data.

_ Name resolution. Provided by the Domain Name System, or DNS, protocol. DNS enables people to use easy-to-remember names like www.microsoft.com and allows computers to translate those names to numeric IP addresses.

_ Windows Internet Name System (WINS). Prior versions of Windows also use WINS to convert computer names into IP addresses. Windows Server 2003 is compatible with WINS.


    We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths.

― Walt Disney

 
References:
Sybex(2003): Mastering Windows Server 2003


Wednesday, July 3, 2013

Understanding Engineers

 The following is a collection of quotes gleaned from the pages of pprune.org replicated here for your enjoyment :-)

Understanding Engineers #1
Two engineering students were biking across a university campus when one said, "Where did you get such a great bike?" The second engineer replied, "Well, I was walking along yesterday, minding my own business, when a beautiful woman rode up on this bike, threw it to the ground, took off all her clothes and said, "Take what you want." The first engineer nodded approvingly and said, "Good choice: The clothes probably wouldn't have fit you anyway."

Understanding Engineers #2
To the optimist, the glass is half-full. To the pessimist, the glass is half-empty.
To the engineer, the glass is twice as big as it needs to be.

Understanding Engineers #3
A priest, a doctor, and an engineer were waiting one morning for a particularly slow group of golfers. The engineer fumed, "What's with those guys? We must have been waiting for fifteen minutes!"
The doctor chimed in, "I don't know, but I've never seen such inept golf!"
The priest said, "Here comes the greens-keeper. Let's have a word with him."
He said, "Hello George, What's wrong with that group ahead of us? They're rather slow, aren't they?"
The greens-keeper replied, "Oh, yes. That's a group of blind firemen. They lost their sight saving our clubhouse from a fire last year, so we always let them play for free anytime!."
The group fell silent for a moment.
The priest said, "That's so sad. I think I will say a special prayer for them tonight."
The doctor said, "Good idea. I'm going to contact my ophthalmologist colleague and see if there's anything she can do for them."
The engineer said, "Why can't they play at night?"

Understanding Engineers #4
What is the difference between mechanical engineers and civil engineers?
Mechanical engineers build weapons . Civil engineers build targets .

Understanding Engineers #5
The graduate with a science degree asks, "Why does it work?"
The graduate with an engineering degree asks, "How does it work?"
The graduate with an accounting degree asks, "How much will it cost?"
The graduate with an arts degree asks, "Do you want fries with that?"

Understanding Engineers #6
Three engineering students were gathered together discussing who must have designed the human body. One said, "It was a mechanical engineer . Just look at all the joints".
Another said, "No, it was an electrical engineer. The nervous system has many thousands of electrical connections".
The last one said, "No, actually it had to have been a civil engineer. Who else would run a toxic waste pipeline through a recreational area?"

Understanding Engineers #7
Normal people believe that if it ain’t broke, don't fix it.
Engineers believe that if it ain’t broke, it doesn't have enough features yet.

Understanding Engineers #8
An engineer was crossing a road one day, when a frog called out to him and said, "If you kiss me, I'll turn into a beautiful princess".
He bent over, picked up the frog, and put it in his pocket.
The frog spoke up again and said, "If you kiss me, I'll turn back into a beautiful princess and stay with you for one week".
The engineer took the frog out of his pocket, smiled at it and returned it to the pocket.
The frog then cried out, "If you kiss me and turn me back into a princess, I'll stay with you for one week and do anything you want".
Again, the engineer took the frog out, smiled at it and put it back into his pocket.
Finally, the frog asked, "What is the matter? I've told you I'm a beautiful princess and that I'll stay with you for one week and do anything you want. Why won't you kiss me?"
The engineer said, "Look , I'm an engineer. I don't have time for a girlfriend, but a talking frog - now that's cool".



Saturday, June 1, 2013

Networking Questions - Cisco based

Another interesting set of Questions to help you on your way to certification - or as a refresh - enjoy.

1. How many access control lists can you apply to an interface?

A) Unlimited
B) One ACL per port per direction
C) 10
D) You do not apply ACL to interfaces


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

A) True
B) False


3. What class of routing protocol is EIGRP?

A) Link state
B) Distance vector
C) Hybrid


4. Where would you place standard access lists?

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


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

A) True
B) False








1. Correct Answer: B
Cisco routers only allow you to place one access control list (ACL) per direction. One inbound ACL and one outbound ACL. However you can add multiple statements to these access lists.


2. 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. 


3.  Correct Answer: C
EIGRP is a hybrid routing protocol which uses a combination of distance vector and link state methods to determine the best path.


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

5. Correct Answer: A


How did you go? More Questions coming, stay tuned...




Tuesday, May 21, 2013

Cisco based exam questions part ix




Random networking questions for those curious, wanting to refresh or studying for Cisco certification.




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

A) True
B) False


2. What is the invalid timer set to by default when you have a router running the Interior Gateway Routing Protocol?

A) 3 times the update period
B) 270 seconds
C) 3 times the update period + 10 seconds
D) Answer A and B
E) 7 times the update period 


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 OSI layer does the following refer to?

"Establishes availability of intended communication partners, establishes agreement on procedures regarding error recovery and data integrity and synchronizes networked applications"

A) Transport layer
B) Session layer
C) Datalink layer
D) Application layer
E) Presentation layer


5. Which of the following protocols do not form part of the TCP/IP Internet Layer?

A.) IP
B.) ICMP
C.) FTP
D.) ARP
E.) RARP









1. Correct Answer: B

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


2. Correct Answer: D

Explanation
IGRP sends its routing table to its neighbors every 90 seconds. IGRP uses an invalid timer to mark a route as invalid after 270 seconds (three times the update timer). IGRP uses a flush timer to remove a route from the routing table (default flush timer is 630 seconds, seven times the update period).


3. Correct Answer: B

Explanation
3 ways of assigning a switched port to VLANs:

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


4. Correct Answer: D

Explanation
The Application layer of the OSI model (layer 7) establishes availability of intended communication partners, establishes agreement on procedures regarding error recovery and data integrity and synchronizes networked applications.


5. Correct Answer C

Explanaition
FTP is an application layer protocol and not part of the TCP/IP suit.






Tuesday, May 14, 2013

Cisco exam questions part viii




Another set of mixed up networking questions to get the grey matter ticking - enjoy.





1. By default is CDP enabled or disabled on compatible devices?

A) Enabled
B) Disabled


2. What is the default setting on a router for the invalid timer if you are using IGRP?

A) 90 seconds
B) 30 seconds
C) 280 seconds
D) 270 seconds
E) 180 seconds


3. What are the default metrics of IGRP?

A) Delay, Bandwidth
B) Load, Reliability
C) Reliability, Bandwidth
D) Delay, Reliability


4. What WLAN standard operates in the 5GHz band with a data rate of up to 54Mbps?

A) 802.11a
B) 802.11b
C) 802.11g
D) 802.11h
E) 802.11n


5. Where is the best position to place an Extended ACL?

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






1. Correct Answer: A

Explanation
CDP is enabled on Cisco routers by default. To disable CDP use the no cdp run command.


2. Correct Answer: D

Explanation
IGRP sends its routing table to its neighbors every 90 seconds. IGRP uses an invalid timer to mark a route as invalid after 270 seconds (three times the update timer). IGRP uses a flush timer to remove a route from the routing table (default flush timer is 630 seconds, seven times the update period).


3. Correct Answer: A

Explanation
IGRP and EIGRP use multiple metric parameters to calculate their composite metric.  These are bandwidth, delay, load, and reliability. By default, IGRP chooses a route based on bandwidth and delay.


4. Correct Answer: A

Explanation
802.11a operates in the 5GHz band with a data rate of up to 54Mbps and is immune to interference from other devices operating in the 2.4GHz spectrum.


5, Correct Answer: B

Explanation
The general rule is to place standard ACLs as close to the destination as possible and to position extended ACLs as close as possible to the source of the traffic that will be denied. This is because extended ACLs can take in to account source and destination addresses as well as port numbers.






Friday, May 10, 2013

How TCP and UDP work



Transmission Control Protocol (TCP) and User Datagram Protocol (UDP)is a transportation protocol that is one of the core protocols of the Internet protocol suite. Both TCP and UDP work at transport layer TCP/IP model and both have very different usage.




Lets imagine, that we need to transfer certain amount of data. You may transfer only certain amount at the time (you have limitation on the packet size, which is below TCP/UDP).

In case of TCP, first you should establish connection (you may read about "3-Way handshake"). During this you agree on the "TCP Window Size" (explained  below). Then you start actual data transfer...

You transfer a packet, and then you wait for a confirmation, that the packet received. If you didn't receive confirmation within certain amount of time, you transmit the same packet again (Retransmission occured). If you agreed on certain "TCP Window Size", you may transmit multiple packets without waiting for a confirmation, and then you receive one confirmation for all these packets (not many, usually a few, just "more than one"). If you sent 3 packets, but only two confirmed, you will send that missing packet, if no confirmation was received at all, then you send all 3 packets again. But the bottom line is - each and every packet should be confirmed.

TCP has tweaked for performance over the years. ACKs are often piggy-backed with replies to messages so there is no extra packet or waiting. It can also dynamically adjust to changing network performance with features like slow start and congestion avoidance. TCP optimizes the amount of data sent per packet to avoid IP fragmentation. With UDP, if you send a message greater than 1472 bytes (for 'normal' Ethernet) the IP layer will fragment it into multiple datagrams and it will buffered and re-assembled in the receiving stack.


In case of UDP, you just blindly split your data into packets, and transfer them without any care, if they were received or not. You may do it "at the wire speed". And if you need some kind of control over the data, this should be taken care on higher layers of OSI model (for example, you should implement transfer verification at the Application Layer).


So, in theory, TCP actual performance is at least twice slower (for example, your one-way-trip time is 100ms, you sent a packet, and wait for a response), plus depends on receiver (how long it takes to prepare and send a confirmation), while UDP may send packets "as a stream" without any delay.

That said, there are many case where UDP may be a better choice. there isn't much use for retransmissions with applications like VOIP. For a simple exchange where you don't need the overhead of establishing and tearing down a connection UDP is likely the way to go, DNS being a perfect example. Note that even DNS will switch to TCP when the server sees that the reply will be lengthy due to multiple addresses and/or MX records.

If you are creating a VoIP application, there is no need constantly to check if the other end is on-line, so you can use UDP to transfer the main payload (voice) and a second TCP connection to handle connection/disconnection at a lower speed (once a second is ok).

If you are transmitting a public radio station over IP, you need only to enable your players to join one multicast channel. In the latest case, UDP is far more effective and is causing less overhead, since all the network balancing is handled by the multicast enabled routers.

In areas of video streaming and VoIP the overhead of TCP would be intolerable, so they use UDP and they work pretty well- mainly because the network infrastructure and the protocols have "matured" to the extent where reliability is largely taken for granted.



Clear as mud?



Thursday, April 25, 2013

Changes to CCNA exam 2013

What changes are Cisco making to the CCNA?

Cisco has made some changes to Associate-level certifications and also renamed the CCNA certification to CCNA Routing and Switching certification. 
The CCNA certification has changed from a foundation certification to a concentration certification.

How is the CCNA Routing and Switching different from the current CCNA?


CCNA Routing and Switching is the same certification as the CCNA, however the syllabuses for ICND1, ICND2 and CCNA Composite have been changed to keep up with technology advancements and job roles.

Are the CCNA Routing and Switching exams changing?


Yes, the exams are changing due to the new syllabuses. The current CCNA/CCENT/ICND2 exams will be retired on September 30, 2013.

How are the new exams harder than the current versions?


Yes, Cisco has taken topics from the ICND2 and included them in the ICND1 exam, such as OSPF, NAT, IPv6 and VLSM subnetting, making the CCENT certification a much tougher assignment.
The new ICND2 exam will include some topics from the CCNP such as multi-area OSPF, OSPF3, Sysylog, Netflow and EtherChannel. This really makes the CCNA Routing and Switching certificate a hard-to-get cert.

Can I mix and match the current exams with newer exams to achieve CCNA Routing and Switching?


Yes, you can mix current ICND1 exam with newer ICND2 exam or vice versa. However, note that several topics have been added to the new ICND1 and ICND2 syllabus. So if you take the new versions of these exams then you need to be prepared to answer questions on the new topics.

What has changed between the current ICND1, ICND2, and CCNA Composite exams and the newer versions of these exams?


To ensure the certifications are up-to-date with current technology, some older topics have been removed from the syllabus and several new topics have been added.
If you take the new versions of these exams then you need to be prepared to answer questions on the new topics.

What new topics are in the new CCNA Routing and Switching exam?


More emphasis on IPv6
High availability via FHRP
Multi-area OSPF and OSPF3
SNMP v1 and V2, SYSLOG and Netflow
NTP (Network Time Protocol)
Be able to troubleshooting everything!
Have I wasted my time learning the current CCNA?
No, the fundamentals of networking do not change, the new exams include some new topics and some have been removed, but the bulk of the syllabus will remain unchanged.

I bought a training package from your company recently, is it up-to-date?


Yes. So as long as you take your exams by 30 September 2013 and pass you will be CCNA certified. Your goal should be to pass by 30 September 2013, which gives you 6 months. We will update our training materials for the new syllabus in due course should you need to sit the new exam.

Should I stop my studies and wait to study the new version?


We advise you to continue studying and aim to take the exam before 30 September 2013. If you wait for the new version you will only delay your career. You'll probably have to start studying from the beginning again, and the new exam will be tougher than the current version.

Is the ICND2 exam required to achieve the CCNA Wireless, CCNA Voice, or CCNA Security certifications?


No. From March 26, 2013, you will only need to pass the ICND2 exam to achieve the CCNA Routing and Switching. You will only need to have a valid CCENT as a prerequisite for CCNA Wireless, CCNA Voice, or CCNA Security certifications.

Is the ICND2 exam required to achieve the CCDA certification?


No. From October 1, 2013, you will only need to have a valid CCENT, or CCNA Routing and Switching or any CCIE certification as a prerequisite.

My CCNA expires within 12 months, what should I do?


We strongly recommend you to recertify before the end of September 2013 before the current exams are retired, otherwise you will need to learn the new syllabus and take the new CCNA Routing and Switching exam.

What are the recertification requirements for the new CCNA Routing and Switching?


The CCNA Routing and Switching certification is valid for three years, then you will need to recertify just like the current CCNA.

Monday, April 8, 2013

More Random Networking Questions

Here's another set of Cisco based 
networking questions, 
They may assist with your gaining certification 
or just as a refresher - enjoy!

1. Which of the following could be a valid MAC address?

A) 00-08-74-CE-B7-90
B) 192.168.0.1
C) FFFF.FFFF.FFFF.FFFF
D) 255.255.255.240


2. Fragment Free 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 the destination MAC address
C) Filters out collision packets by waiting for the first 64 bytes of data


3. A CIDR value of /30 equates to what subnet mask?

A) 255.255.255.253
B) 255.255.255.128
C) 255.255.255.248
D) 255.255.255.252


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

A) True
B) False


5. 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


6. What OSI layer does the following refer to?

"Establishes availability of intended communication partners, establishes agreement on procedures regarding error recovery and data integrity and synchronizes networked applications"


A) Transport layer
B) Session layer
C) Datalink layer
D) Application layer
E) Presentation layer




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1. Correct Answer: A

The standard format for printing MAC addresses is six groups of two hexadecimal digits, separated by hyphens (-) or colons (:) e.g. 00-08-74-CE-B7-90, 00:08:74:CE:B7:90.
Another convention commonly used is three groups of four hexadecimal digits separated by dots e.g. 0573.4567.19ab.


2. Correct Answer: C

Fragment Free is also referred to as Modified Cut-Through. It is the default mode used by Cisco® Catalyst® 1900 series switches. This switching method is the same as with Cut-Through except the switch will check the first 64 bytes of every frame received as this is where the vast majority of errors occur within a frame.

3. Correct Answer: D

4. 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.


5. 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.


6. Correct Answer: D

The Application layer of the OSI model (layer 7) establishes availability of intended communication partners, establishes agreement on procedures regarding error recovery and data integrity and synchronizes networked applications.




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A business absolutely devoted to service will have only one worry about profits. 
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Monday, April 1, 2013

CCNA exam questions part vii

The following is a selection of exam type questions for computer networking, specifically pointed toward CCNA certification.  Good to get the grey matter clicking as a refresher as well, enjoy!


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

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


2. What is port 53 used for?

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


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. Where is the start-up configuration file held in a (Cisco) router?

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

5. A CIDR value of /30 equates to what subnet mask?

A.) 255.255.255.253
B.) 255.255.255.128
C.) 255.255.255.248
D.) 255.255.255.252


6. Where would you place standard access lists?

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




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1. Answer B

2. Answer D

3. Answer D
 
Explanation: Frame tagging is used to tags frames on trunked links to identify what VLAN they belong to.


4. Answer A

5. Answer D

6. Answer A

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


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Saturday, March 30, 2013

Cashing in on Mobile Phones



Most people cannot live without their phones. 

They like the convenience of talking on the road and the safety it provides in an emergency.  But did you know you can do more?  You can.  In fact, you can make money with mobile phones, here are five options to consider:




1 – Open a Mobile Phone Store
If you want to capitalise on the popularity of mobiles, you should sell them.  You can do so through an online store, a brick and mortar store, or both.  When selling mobile phones, you find a wholesale supplier with cheap prices and buy phones and accessories in bulk.  You then, in turn, sell them to consumers.  If operating a full-time store, you can develop a partnership with providers to not only sell phones, but plans too.  In this aspect, you not only make money through the phones, but commission with plans too.

2 – Open a Franchise Store

If you don’t want to spend months developing a business plan or researching wholesale suppliers, you can opt for a franchise opportunity.  A number of well-known and reputable mobile phone stores have franchises available for sale.  With a franchise, you are in charge of your store, but you get a solid business model to follow, as well as other helpful, profitable tips and support.

3 – Sell Mobile Phones Online


If you want to sell mobile phones full-time, you are encouraged to have both an online store and a brick and mortar store.  On the other hand, if you are only interested in working part-time, you can turn to the internet.  Instead of operating a functioning store, you can rely on other websites to help you.  These websites may include eBay.com, Craigslist.org, and so forth.  Also, many message boards have buy, trade, and sell sections.  This approach is nice, as you do not need a shop full of mobile phones.  You can sell them as you buy them.

4 – Work as an Affiliate Seller

If you want to make money with mobile phones, but do not have the financial resources needed to buy products to sell, consider affiliate programs.  By working as an affiliate, you partner with a company.  That company gives you text links, banners, coupon codes, and more.  You place these on your website.  Each time a sale is made, you generate income. Your startup costs are low, as affiliate programs are free to join.  All you need is a website with applicable content.  Good topics are those that focus on mobile phones and accessories, such as product reviews and buying guides.

5 – Through Website Advertisements

Many well-known cell phone providers and mobile phone stores pay you commission for each sale you help to generate.  In addition to this approach, you can outright sell advertisements.  For example, you can charge $25 a month for good advertising space.  This does not seem like a lot, but it will significantly add up with the more space you sell.  With this approach, you earn money each month even if a sale isn’t generated through your website.


As for which approach is best for you, it depends on what you want out of life,
 the choice is yours.


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Monday, March 25, 2013

CCNA networking quick questions

Another random assortment of Cisco based networking questions you can use as a primer for achieving CCNA certification or as a refresher.  

Scroll to the bottom for examination tips .. 

1.  How many IP access lists can you assign on an outbound interface?

A.) 1
B.) 1-100
C.) Unlimited


2. 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


3. What happens if a packet does not match any of the ACL statements?

A.) Nothing
B.) It is rejected
C.) It is allowed


4. Protocol Data Units of the Physical layer are called?

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


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

A.) True
B.) False









1.  Correct Answer A

2.  Correct Answer B

3.  Correct Answer B

4.  Correct Answer A

The Layer 1 (Physical Layer) PDU is the bit
The Layer 2 (Data Link Layer) PDU is the frame
The Layer 3 (Network Layer) PDU is the packet
The Layer 4 (Transport Layer) PDU is the segment


5.  Correct Answer A




Here are some revision tips to help you revise for the CCNA exam, or any Cisco exam for that matter...

1.)  Make sure you only learn topics which are covered by the exam.
2.)  Glance through the course/exam topics and highlight the areas you think you'll need to concentrate on more.
3.)  Get a good CCNA book that suits your learning style.
4.)  Practice what you learn frequently by using practice tests and flash cards. Highlight your weakest subjects and aim to improve them.
5.)  Create a set of revision notes for each topic. Try to stick to one page of paper per topic.
6.)  Read through your revision notes frequently.
7.)  You want to retain the information beyond the exam, so forget about cramming the night before the exam. Spread out your revision into 30 minute revision periods.
8.)  Condense your revision notes. The act of rewriting them will help you memorize them.
9.)  Practice your IOS configuration on a Cisco router or router simulator.

Monday, March 11, 2013

More CCNA Networking Questions for you

Here are a bunch of Cisco based networking questions to ponder.  These are the kinds of questions you may find if you study Network engineering, so i hope they may assist you in your endeavors..or just for fun :-)

1. What TCP/IP Application layer protocol polls devices on the network helping to notify when network errors occur?

A) Telnet
B) FTP
C) SNMP
D) LPD
E) SMTP


2. 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


3. What TCP/IP layer are ICMP, ARP and RARP protocols associated with?

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


4. Hosts on one VLAN that want to communicate with another VLAN need to go through a router.

A) True
B) False


5. Which of the following are Routed protocols?

A) IP, IPX, ICMP
B) IP, IPX, Appletalk
C) RIP, IGRP, EIGRP


6. What does the Spanning Tree Protocol achieve?

A) Determines a loop free topology
B) Sets up a meshed switched topology
C) Creates bridge loops and broadcast storms
D) Disseminates VLAN topology




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1. Correct Answer: C

2. Correct Answer: C

Explanation: 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.


3. Correct Answer: C

4. Correct Answer: A

Explanation: VLANs act as if they are different networks.  So communication between VLANs require routers.


5. Correct Answer: B

Explanation: 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.


6. Correct Answer: A

Explanation: Spanning Tree Protocol (STP) is a Data Link protocol that ensures a loop-free topology for bridged or switched LANs. The algorithm prevents bridge loops within the network that cause broadcast storms, while allowing redundant links.


“Insanity is doing the same thing, over and over again, but expecting different results.”
- Narcotics Anonymous