Interesting Technology

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...

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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

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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

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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?

Monday, April 29, 2013

Review: Samsung Galaxy S4 smartphone - Telco/ISP - Technology - Reviews - iTnews.com.au

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

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.

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.