Top 5 Simple Electronic projects

Discrete component circuits.oh the memories...

  

 Man I miss playing with this kind of stuff. 

 I've still got boxes full of transistors, LED's, diodes, resistors etc might have to break them out and remind myself why I became a tech :-)

 

 

A new series of Cisco base networking questions for 2014 - part2

A set of questions for those interested in IT / networking / certification or just generally curious  - Enjoy.

(This time with some IPv4 questions thrown into the mix :-)

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

1. 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

2. What is the maximum number of subnets and hosts per subnet achievable from the network 172.22.0.0 255.255.255.224?

A) 2048 subnets and 30 hosts
B) 256-224=32 ip per subnet - 30 hosts
C) 256/32=8 subnets per 4th octet
D) 256 x 8 = 2048 total subnets for B class address


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 is the default time BPDUs are sent and received by switches?

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

5. 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









1. 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

2. Correct Answer: A

2048 subnets and 30 hosts

3. Correct Answer: B

Three ways of assigning a switched port to VLANs:

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

4. Correct Answer: A 

The Spanning Tree Protocol (STP) is a network protocol that ensures a loop-free topology for any bridged Ethernet local area network. The basic function of STP is to prevent bridge loops and the broadcast radiation that results from them. Spanning tree also allows a network design to include spare (redundant) links to provide automatic backup paths if an active link fails, without the danger of bridge loops, or the need for manual enabling/disabling of these backup links.

The bridges have to determine the root bridge and compute the port roles (root, designated, or blocked) with only the information that they have. To ensure that each bridge has enough information, the bridges use special data frames called Bridge Protocol Data Units (BPDUs) to exchange information about bridge IDs and root path costs.

A bridge sends a BPDU frame using the unique MAC address of the port itself as a source address, and a destination address of the STP multicast address 01:80:C2:00:00:00.

There are two types of BPDUs in the original STP specification (The Rapid Spanning Tree (RSTP) extension uses a specific RSTP BPDU.[4]):

Configuration BPDU (CBPDU), used for Spanning Tree computation
Topology Change Notification (TCN) BPDU, used to announce changes in the network topology
BPDUs are exchanged regularly (every 2 seconds by default) and enable switches to keep track of network changes and to start and stop forwarding at ports as required.

5. Correct Answer: A

"No" is generally used in front of Cisco config lines to remove them from configuration, in this case No Removes Access List 1

More questions Coming - see you soon...

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The Roots Of Radio Hobbyists

Radio hobbyists can play with their equipment all day without giving a thought to the origins of their hobby. Early radio hobbyists were part of something that was, at the time, new and fairly crazy.

After radio technology was stabilized, there was a steady growth of radio signaling in the fields of navigation of ships and for rescue operations. On the other hand, the amateur radio operators also started to dominate the air. The first documented and famous amateur wireless enthusiast was a then young man named Irving Vermilya born in 1890 when wireless transmission was being born. The young man since age 12 heard Marconi and built his own wireless transmission equipment and was often "heard" telegraphing with ships during that time. In 1911 he became a member of the Radio Club that had been formed. He got himself certified in 1912 when law mandated all wireless operators to be certified. In his own words,

This was pre-audio era, and communication was purely in Morse code. Irving then organized his own amateur group who had regular meetings monthly and would communicate daily wishing "GM" (good morning) and "GN" (good night), some of the first amateur jargon to be used. He also proceeds to describe in his series of articles published in QST magazine in 1917 as to how they managed to lay the telegraph lines and such and how they "drew juice" for the wireless operation from the electric lines instead of relying on batteries.

Meanwhile, apart from the "professionals" and "amateurs", with audio wireless signal transmission there was a new revolution setting in. A Dutch engineer in Hague was the first to make regular wireless transmission via radio. This could be considered the first regular radio broadcast. After this there was slow development until the commercial radio stations came into being.

The requirement to be certified killed the enthusiasm in many amateurs, and the number of amateurs dwindled. But then after WWI, there was a boom. The first radio clubs were formed in 1909 and this was the beginning of the radio hobbies which included radio as a part of the hobby activity.

During the WWI the amateur radio operators were asked to stop their activity and dismantle the equipment. Radio operators in uniform helped in military communications. They got back on the air again by November 1919 again. A similar lull in amateur radio happened during Second World War and got back on air by 1946. After lots of battles over the frequency range that the amateurs can tune into, the amateur radio is here to stay!

At present there are more than 170,000 ham operators which is possibly not the complete picture. It is still increasing. So, with Irving Vermilya was born the amateur radio operation, since he was the first radio hobbyist. After lots of developments, including the discovery of the transistor which greatly decreased the size of the radio equipment, the old ways still remains which included "waiting for someone to signal".

The rules to get oneself certified and licensed included a Morse code proficiency until the World Radiocommunication Conference in Geneva in 2003 that eliminated the need for Morse code proficiency from the licensure tests. Taking effect from February 23, 2007 the Morse code has been eliminated from the tests for amateur radio license tests.