Cisco CCNA, CCNP, CCENT Practice Questions: VLANs, IPv6

CCENT Certification:

Given the MAC address aa-bb-cc-11-22-33, identify the OUI.

Answer: The OUI is the first half of the MAC address, aa-bb-cc.

CCNA Certification:

Short answer: A frame is about to be transmitted over a trunk. What term describes the process of identifying the destination VLAN?

Answer: This is known as “tagging” the frame.

CCNP Certification / BSCI Exam:

Fill in the blank: An IPv6 address consists of ____________ bits.

Answer: 128 bits.

CCNP Certification / BCMSN Exam:

Approximately how long does it take a switch running RSTP to detect a down link?

A. 20 seconds (the MaxAge value).

B. 2 seconds (the Hello Time value).

C. 15 seconds (the Forward Delay value).

D. None of the above.

Answer: D. An RSTP port will detect a down link in about 6 seconds. When a RSTP port misses three BPDUs, the link is considered down. The RSTP Hello Time is 2 seconds.

CCNP Certification / ISCW Exam:

You’ve just created an IP inspection rule. How should it be applied?

A. Globally.

B. On a per-protocol basis.

C. On a per-interface basis.

D. On a per-access list basis.

Answer: C. IP inspection rules are applied on a per-interface basis.

CCNP Certification / ONT Exam:

Which of the following is NOT a service class found in the Customer Model service class?

A. best-effort

B. guaranteed

C. mission critical

D. scavenger

E. transpositional

F. collapsed core

G. scavenger

Answers: B, E, F. The service classes in the Customer Model are mission critical, best-effort, scavengerComputer Technology Articles, and transactional.

Home Network Data Storage

If you have two or more computers at home that are wired together to share resources, then you have a home computer network. Anyone who uses a computer, which encompasses almost everyone, should be aware of the need to back up important data. There are options available for network data storage that may not be available for the single computer. The first step in deciding how to conform your network data storage is to determine the type of backup you should use. Usually a backup is done by making a copy of all of the existing files, like a snapshot in time, and then adding backups of the changes as they occur. The other decision to make is the location of where to keep the backups.

Here, There and Everywhere

If you don’t store very much on your home computer network, you may be able to manage your home network data storage project on DVD’s. With a small amount of information needing backup, you might just use rewritable DVD’s and make a full copy of chosen files as needed. If there is one or more computers on your network that is primarily used for internet use, email, web surfing and games, then the need for data backup is limited. The benefit of this type of home network data storage is that you have control over whether or not to back up a file and you choose how often to do the backups. The downside that many people don’t update their backups often enough and frequently the discs become lost or damaged due to inadequate storage practices.

The next step up is to create a server to store backup files for all of the computers on the network. A server is simply a hard drive, and software is available for small home networks. There are also network-attached storage (NAS) devices which act as a dedicated backup server. The benefit here is that the software can be set to automatically perform backup procedures at regular intervals. The drawback is that the backups are in the same place as the computers, and may fall victim to whatever type of disaster makes it necessary to use the backups.

Finally, there are remote services that will automatically use the Internet for home network data storage. Once signed up, the user is charged according to the amount of storage is needed. The benefit is that data is stored remotely and the updates are automatic. Drawbacks are that large amounts of data can be costly and that it’s only as reliable as the company. The decision on the type of home network data storage to use is based on the needs and resources of the network users.

Proxy Servers Explained

On the web network, there are a lot of websites which offer features like file-sharing, instant messaging or leaving comments for the user’s profile. A lot of schools and universities have blocked such websites to be accessed from their locations to restrict people from logging in to these websites. But the use of proxy servers has a technological advance over these restrictions. The Proxy servers let you access websites from restricted locations and are a source to bypass secure sites from blocked locations, as they have the ability to bypass the network firewalls and filters. These proxy servers enable the users to surf the internet from blocked servers and are compatible to surf through sites which have audio and video streaming platforms like Youtube.

A proxy server is a computer program or application which processes a client request and forwards it to other servers. When you connect to a proxy server, and try to access some information available on another server, it forwards the request on your behalf and acts as the host server. In short, it becomes your face and represents you for access to the website or information. There are lots of types of proxy servers available based on your need, such as;

&bullWeb proxy
&bullCaching proxy server/ Http proxy
&bullAnonymous proxies
&bullIntercepting proxies
&bullHostile proxy servers
&bullReverse proxy servers
&bullForced proxy servers.

Usage of these proxy servers requires a simple process to be followed. You have to sign up to be able to use these proxies. Most of these proxy websites offer services without a cost. But, some of them may ask for a small fee to for the proxy services. After signup, the user can type the desired URL (for example: www.myspace.com) on the main page and all connections and traffic to and from the destination URL is redirected via the proxy, making it look as if the traffic is evolving from the main proxy , thus bypassing the domain based URL filtering blocking system. These proxies allow users to browse through the restricted websites and view profiles, post comments, blogs and surf the sites for music.

These proxies are reliable and secure. You have to agree to accept the strict set of terms and conditions like not to access websites that contain illegal content such as ware sites, use for spamming purposes, or distributing Spy ware or any other malicious script and you can surf the internet at school, universities, work and other places without any restriction, using the simple scripts which allow you to access the blocked websites.

Network Time Synchronization & Accurate Time Server

Each PC has an integral real-time clock that maintains internal system time. PC clocks have low-cost crystal oscillators that are notoriously prone to drift. With time each computer in an organisation drifts at different rates. After a relatively short period of time, there can be large differences between the system times of each computer on the network. Unsynchronised computer time can lead to many problems.Computer TimeComputer system time is maintained by low-cost real-time clock and crystal oscillator components. Crystal oscillators are manufactured with relatively low tolerance; each one oscillates at a slightly different rate. Additionally, crystals change frequency slightly with temperature variance. This all has the effect that computers are notoriously poor at maintaining an accurate time. Each computers time in an organisation will drift at slightly different amounts unless they are synchronised in some way.

Network Synchronisation IssuesPoor network time synchronisation can cause a number of problems. In a transaction-processing environment, transactions generated from various PC’s may have an irregular time-stamp. Unsynchronised computers may be vulnerable to fraud, particularly in an environment where transaction time is an important issue. Additionally, problems can arise with shared network files, if computers with unsynchronised system times are using the same resource.

Network Time ServersNetwork time servers obtain accurate time from an external time reference and offer an accurate time resource to network time clients. Time servers utilise the Network Time Protocol (NTP), which is a UDP based protocol over TCP/IP. A number of external time references are available, such as GPS and regional radio frequency transmissions. The GPS (Global Positioning System) is a subscription free service that offers highly accurate time. GPS antennas require a good view of the sky in order to obtain timing information. Regional time and frequency transmissions include: MSF transmitted from Rugby (UK) with coverage of the British Isles and North-Western Europe; DCF-77 transmitted from Frankfurt (Germany) with coverage of much of Central Europe; WWVB transmitted from Colorado (US) with coverage of much of the US and Canada. Other regional radio time reference include: TDF (France); CHU (Canada); JJY (Japan) and HBG (Switzerland).

Internet Time ServersThere are many Internet based NTP time server resources available that can be utilised for network time synchronisation. However, utilising an Internet time server can have a number of issues. The time server is located outside of the firewall, so a port must be left open in order to access the time server. This obviously has security implications. Additionally, time server accuracy, reliability and provision of service may be problematic.

Local Dedicated Network Time ServerA local dedicated network time server overcomes many of the issues associated with Internet based references. A local time server is located inside the security firewall and so requires no external access, negating security issues. Additionally, a local time server will have improved accuracy due to consistent network paths between clients and server. Also there is no provision of service issues since the time server is owned by the organisation where it is installed.

SummaryNetwork time synchronisation is an important factor in modern computer network installations. Internet based network time servers may provide a solution to network synchronisation, but there are security issues that arise with there use. Local dedicated network time servers overcome the security and accuracy issues with internet based services by providing a secureFree Reprint Articles, accurate and reliable network time synchronisation solution.

Computer TV Software Reviews- Software Reviews for Online TV

This is basically a software that enables you to watch satellite TV via your computer. The computer TV softwares are configured to automatically access the internet websites of TV networks, logging you in to video and audio TV streaming via the internet.

The nature of online TV is that it is global and therefore is available all over the world. Likewise, there are over 70 different countries TV networks featured in any one satellite TV software for computers. What then this does for you is avail over 3,000 free world TV tuner stations at the touch of a mouse.

How do I get TV on my computer?

There are three main ways that you can view computer on TV.

Computer to TV Connector by Using Free TV Online Websites

The first and absolutely free way to display computer on TV is by accessing the free online TV websites. There are several websites that offer free satellite TV for PC including beeline.com, channelchooser.com and many others.

Due to the large number of people looking for free TV, these websites are usually congested and you will be lucky to watch free online TV for more than 10 minutes straight. You could give it a shot after reading this article just to make sure.

Free TV on computer through installing PC TV cards

The other method get TV on your computer is by buying one of those PC TV cards. These are slotted into your computer and come with an inbuilt TV tuner toolbar that you activate by use of a special PCTV software. If you have no knowledge on the internal workings of your computer hard drives, you will be better off hiring the services of a computer technician to manually install the PCTV card.

An external aerial is required in order to receive the TV signals from satellite transmitter stations. The broadcasts you will receive are mostly Free-To-Air TV channels but at least you will be able to capture such news channels like BBC, CNN, ABC, CBS and FOX News.

Computer TV software-What are they and how do they work?

The last method that you can watch TV on your computer monitor is by download of a computer TV software. This is the more recent development that enables you to capture satellite TV through the internet. Unlike the free online TV websites, this method of accessing TV online is not congested.

You are able to watch seamless video and audio TV streaming from many global countries. This method of watching internet TV is especially useful to people living ways from home in a third country.

The Computer TV softwares are especially a favorite with Expats, travelers, people on mission work in Africa, diplomats, and immigrants to the USA. The TV softwares for computer offer over 3000 TV channels to chose from and TV is available in over 70 languages.

Read More Reviews on how to Watch TV on Computer Monitor

You can read more reviews on satellite TV softwares for computer downloads at the links given below in the author’s box or see a demo of picture quality by following through with links from the blog.