CCNA Video Training – 2 Best CCNA Video Training Products Compared

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CCNA Tutorial – What You Need To Know About NAT And Routing

This is a CCNA tutorial on how Cisco NAT (network address translation) works.  I wrote previously about how to use the proper NAT Cisco IOS Commands.  This article will provide more detail on the NAT order of operations and routing.

One important point of NAT which is not mentioned in many CCNA tutorials and CCNA books is the NAT order of operations.  Cisco has written a document about the NAT order of operation which can be intimidating to read for the new network engineer or CCNA candidate.  Strictly speaking, you might not need to have this knowledge for the CCNA test, however, this is very useful to know for any practical implementation of NAT, and it’s definitely something within the CCNA level of knowledge.  Read this CCNA tutorial well and you’ll be able to improve your practical NAT knowledge.

The translation is done whenever the packet traveses the router from the NAT inside interface to the NAT outside interface, or the other way round from the NAT outside interface to the NAT inside interface.  In many NAT implementations, there is no dynamic routing configured due to security restrictions in the network DMZ or at the network edge.  In this case, how would you know which routes you need to configure for the NAT to operate smoothly?  Do you need to have routing to the untranslated or translated address?  This is a source of confusion to many network engineers new to networking and the topic I will focus on for this CCNA tutorial.

NAT Inside To Outside

For packets going from the NAT inside to the NAT outside interface (local to global translation), when you check the Cisco order of operations guide, you will find that routing occurs before translation.  In this case, you’ll need a route for the untranslated network or address (in the above diagram, 196.168.100.1).  This can be added statically if no dynamic routing protocol is configured.

Network Address Translation - Incoming Packet

NAT Outside To Inside

For packets going from the NAT outside to the NAT inside interface (global to local translation), routing occurs only after translation.  In this case, you’ll need a route to the post-translation address (in this case 192.168.1.1), NOT the global address as you might expect.

There are other aspects of the NAT order of operation that affect the NAT configuration but by far the routing is the most important to have a functional NAT configuration.  Some other parts of the NAT process such as when the ACLs are checked are also important, and I’ll cover this in an article sometime in future.

I hope this CCNA tutorial has helped improve your knowledge of NAT for the CCNA and beyond.

P.S. Become a fan of SavvyNetCert on FaceBook now. Click here to see our FaceBook page.

Cheers,
Francis (@savvynetcert)

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2 Most Important Topics To Focus On For The CCNA Exam

The CCNA might be intimidating at first, especially since Cisco has expanded the scope of the exam to include more advanced topics such as Open Shortest Path First (OSPF) routing which is traditionally only tested in the CCNP and other professional level exams.  Time management during the exam is the number 1 most important thing to do well.  This means scoring easy points when possible and to spend more time focusing on those questions which are harder.  To maximize the chance of passing the CCNA exam, here are 2 most important (in my opinion) topics to focus on for the CCNA:

Subnetting

Learning how to subnet effectively is the most important thing for the CCNA.  It’s also important to be able to size subnets quickly in the real world for network planning and troubleshooting purposes.  Because the CCNA (and any other certification exam) is a test of your time management skills during the test, and subnetting can be done quickly (and 100% correctly) if you know the right technique, it’s a quick way to score easy points.

Common subnetting questions include calculating the number of hosts in a subnet, finding if 2 hosts are in the same subnet, and deciding on the correct hostmasks, among others.  Being able so solve such questions quickly means that you will be able to free up valuable exam time to solve other questions.  Answering such calculation questions are a matter of simple calculations and it’s hard to get them wrong once you know how.  Again, the key is speed and you will definitely want to get subnetting questions out of the way as quickly as possible.  You might want to take a look at our recommended CCNA books and CCNA notes if you want to be able to learn how to do subnetting well.

Simulation Questions

Simulation questions (commonly now referred to as “sims”) are designed by Cisco to test the practical aspect of Cisco networking.  A simulation of a real Cisco IOS command-line is provided to you and you are expected to troubleshoot or otherwise configure the network to the required specification.

These questions are more time consuming but very important.  Only Cisco knows for sure how these are actually scored but it’s very likely that you won’t get enough points to pass the CCNA if you cannot answer all the simulation questions to a satisfactory level.  The CCNA passing score gets higher all the time, which makes scoring high on the simulation questions a priority.

One good thing about using simulation questions is that you’ll be able to gauge roughly how well you’ve done by showing the running configuration and running other tests such as ping and using other show commands.  A good way to prepare for the exam is to use a Cisco router simulator.

I hope this post has helped you prepare for the CCNA more effectively.  Till next time!

P.S. Become a fan of SavvyNetCert on FaceBook now.  Click here to see our FaceBook page.

Cheers,
Francis (@savvynetcert)

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CCNA Notes – 3 Crucial Things To Know When Choosing CCNA Summary Notes

CCNA notes, also known as CCNA summary notes or exam cram notes are an essential part of preparing for the CCNA.  One of the best known is the Exam Cram CCNA notes book.  Employers these days value troubleshooting skills and hands-on configuration skills to be extremely important when they are deciding which network engineer to hire.  I believe that one of the reasons that Cisco introduced simulation questions into the CCNA is because of this market requirement.

Even with this new focus on practical skills, the fact remains that if you want to pass the CCNA and become an effective networks engineer, you need to remember all the important networking terms.  Factual knowledge such as the OSI model, and the default administrative distances of each of the routing protocols are something that you need to be certain of before taking the exam or trying to apply for an networking job.  In this regard, CCNA notes are very useful as a memory aid which can help you prepare for the CCNA exam.  Here are 3 points to look out for when choosing CCNA notes:

1. CCNA Notes Exam version – This is the most important thing to take note of.  Cisco changes the CCNA syllabus regularly perhaps every 1-2 years.  It is important that all your certification books and notes are up-to-date with the current version of the exam.  This is particularly important as CCNA notes are usually the slowest to get updated when it comes to CCNA study material.  Do check carefully to see if the exam revision stated on the CCNA notes is that of the current exam.  You can check the current exam version at the Cisco.Com.
2. Portability – Portability is something you need to take note of when choosing good CCNA notes.  For the usual CCNA candidate, you would have already attended the CCNA class or read throughly the important CCNA books and just need some study material to jog your memory and improve your recall of the key facts.  At this point in your CCNA revision, you certainly do not want to be carrying thick and heavy books.  Small-sized CCNA notes can be brought anywhere to study and you’ll be able to constantly revise the difficult to remember networking facts wherever you are
3. Qualification of Authors – Although there really isn’t a need to get CCNA notes written by certified CCIEs, it is important that the notes are written by qualified professionals.  Technical material needs to be written in a technically coherent manner in order to be useful for the CCNA exam.  In my opinion, only certified individuals or Cisco trainers will know the best way to present this material.  Do check who is writing the book before you buy.

I recommend the CCNA Exam Cram (Exam 640-802) (3rd Edition) CCNA notes for CCNA exam summary revision.  It comes from the well known Exam Cram series of books and the current 3rd edition is up-to-date for the 640-802 CCNA exam.  It comes in a very portable size and is written by CCNA experts.  I used a previous edition of the book to obtain my CCNA previously and I highly recommend the exam cram series of books for clear and concise CCNA notes.

Cheers,
Francis (SavvyNetCert.Com)

P.S. The CCNA Exam Cram (Exam 640-802) (3rd Edition) CCNA notes is available from Amazon.Com with a 34% discount and FREE shipping.

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CCNA Video Training – CCNA Certification Breakdown

If you’re considering whether to get the CCENT then work on the ICND2 exam, or just take the 1 CCNA exam, you might want to check this video by TrainSignal training.

I now recommend that you always take the CCNA in 2 parts (unless you are re-certifying), just because it costs the same.  The ICND1 and ICND2 exams cost $125 each, and the composite CCNA exam costs $250.  In addition, you’ll be a certified CCENT once you’ve passed the ICND1 and you can start applying for some basic networking jobs based on that certification.

If you want the best in CCNA training, do check out CCNA video training by TrainSignal.

Cheers,
Francis (SavvyNetCert.Com)

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CCNA Network Engineer Tips – An Overview Of Using The OSI Model For Troubleshooting

For any CCNA network engineer, The 7 layer OSI (Open System Interconnection) model can be said to be the most important reference model for networking communications today.  It’s essential to have a good understanding of the OSI model so you can have a common frame of reference with other network engineers in your organization and even elsewhere outside your organization, for example, with service providers and even application developers.

The OSI model is also extremely useful as a basis for network troubleshooting.  One way to do this is to isolate problems and troubleshoot from Layer 1 up to Layer 7.  This is slightly out of the scope of the CCNA exam but it’s still important to know this for practical day to day troubleshooting.  Here is a short overview of what possible issues can happen at the first 3 layers:

1. Physical Layer (Layer 1)- At the physical layer, it’s possible to have some issues with the transmission media.  This includes faulty, malfunctioning or improperly terminated cable, or even something wrong with the switch hardware.  There could also be very low-level errors from the switch or other active media such as signaling or buffering issues.
2. Data Link Layer (Layer 2) – The most common layer 2 protocol is Ethernet.  In an Ethernet network, problems that can occur in the data link layer include misconfiguration of the switch leading to spanning tree loops, broadcast storms as well as other frame forwarding and switching problems.  It is usually quite difficult to troubleshoot issues at layer 2 when they occur, and the convergence time for the spanning tree makes this even more complicated.
3. Network Layer (Layer 3) - Since the majority of networks these days are running IP, the network layer is also commonly referred to as the IP layer, due to the fact that IP addresses reside at this layer.  The most common issue at this layer are routing related problems, due to incorrectly configured dynamic protocols or misconfigured static routes.  Problems at layer 3 are usually easier to isolate when compared to layer 2 issues, however, the potential impact of a routing issue is very high.  If a bad route is inserted into the network and this is redistributed across the entire network, the results could be devastating.

I’ll focus on network issues that can happen at layer 4 in a future article.  Be sure to subscribe to my RSS feed and follow me on twitter so you don’t miss anything!

Cheers,
Francis (SavvyNetCert.Com)

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Cisco IOS Commands – Using Extended Ping For Network Troubleshooting

The extended ping command is a very important part of any network engineer’s Cisco IOS commands knowledge.  Many beginners do not know how to use this command effectively, but it is definitely a must-know and can isolate many network issues.  In this post, I’ll go through some of the most important and useful parameters of this command:

Target IP address

The target IP address is the IP you want to send the ping/ICMP packet to.  This is fairly straightforward, but one important note that if this IP is not routable from this router, you won’t be able to reach it, and will get no replies.  The next step would be to do a traceroute to further isolate the issue.

Repeat count

Some physical line problems might only show up upon repeated ping tests.  If it’s an intermittent issue, it’s best to put a larger number to simulate a stress test in order to ensure that there are no issues.  For example, 1,000 or 10,000 packets might be a suitable number.

Datagram size

For stress test purposes, you can put a larger number in the datagram size to test for larger packets.  It is not recommended to put a datagram size larger than the maximum MTU size of all the routers along the routing path as this would mean the packets would be fragmented (unless you are testing whether fragmentation is working properly).  For an TCP/IP network running on ethernet, a good datagram size to use is 1500.

Some issues might also only show up with larger datagram sizes.  These are usually related to some fragmentation issue along the way.  It makes sense to test with larger datagram sizes as well as small ones in order to be sure.

Source address or interface

This part of the extended ping command is very useful to test whether it’s a routing issue or a switching issue.  If you reach the directly connected router for a problematic host, and pings are successful when sourced from a directly connected interface (but not from another interface which is not directly connected), it usually indicates a routing configuration or process issue on that router, since no routing is needed for directly connected interfaces.

I hope you’ve found this post on Cisco IOS commands useful.  Do subscribe to my RSS feed or follow me on twitter (@savvynetcert) for the latest updates.

Cheers,
Francis (SavvyNetCert.Com – @savvynetcert on Twitter)

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Cisco IOS Commands – Using The Show Interface Cisco IOS Command For Troubleshooting Network Issues

Mastery of Cisco IOS commands is a very important part of the CCNA test and is also essential for anybody who is serious about a career in computer networks.  Of all the commands, the most crucial are those you should have at the tips of your fingers when something goes wrong and you are suddenly called upon to troubleshoot.  Every so often, the issue is related to a switchport and it is important to know how to use the show interface Cisco IOS command properly.  If there is a network issue regarding slowness or disconnects, here are a 6 things you should be looking at when you check on the output of the “show interface” Cisco IOS command:

1. Is the physical port and line protocol up? If you don’t have layer 1 and layer 2 connectivity, there is no way any IP packet is going through this port.

2. Any duplex mismatch issues? Duplex mismatch could lead to slowness and errors in the network.  If the speed does not match, the port won’t even come up.

3. Any QoS drops? If you have a QoS policy in place, it might be shaping and policing the traffic and dropping the packets.  In this case, you might need to either rework your QoS policies, or advise the user about the high traffic levels.

4. What are the traffic levels, is this normal? You can check the input and output rates to see if this is normal for this time of day.

5. Any CRC or other input errors? Input and CRC errors could signify a physical problem with the port or cabling.

6. Any output errors or collisions? Output errors could also indicate a physical issue with the port or cabling.  A full-duplex connection should have no collisions while it is quite normal for a half-duplex port to have collisions.

Cheers,
Francis (SavvyNetCert.Com)

P.S. Still preparing for your CCNA? Have you seen our CCNA book comparison chart?

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CCNA Career Tips – 3 Areas To Focus On In Your New CCNA Job As A Networks Engineer

Developing strong technical skills and core network fundamentals are very important to your CCNA career.  If you want to improve your skills as a qualified CCNA networks engineer, here are 3 areas I suggest you focus on to become effective in your role in the quickest time possible:

1. Troubleshooting Skills

Troubleshooting skills are the bread and butter of any network engineer.  As you progress you might be doing less and less troubleshooting and more deployment, but as a relative beginner it is the single most important skill you should develop as a good CCNA networks engineer.

This is even more evident evident from the newer Cisco exams, which have been structured to have more focus on debugging and fixing problems.  Most of the entry-level jobs are support positions, where you will be identifying and fixing network issues reported by users about 80% of the time.  It is thus important to become good at troubleshooting as soon as possible, so as to be effective.

2. Management of Expectations

Very often problems that arise cannot be easily solved quickly.  Some problems which are more vague in nature like the network being slow or intermittent disconnections can be hard to track down and fix.  More complex and mysterious issues might take from several days to several weeks to fix.  It is important to manage the users’ expectations properly and keep them updated with an estimate of when the problem can be solved.  If not, you might end up with a situation where they will call you every 10 minutes for an update.  This is a very important part of your CCNA career so don’t overlook it.

3. Planning One Step Ahead

The computer network industry is constantly in a state of flux and it is important to be abreast of the latest developments.  In the ideal situation, you should start training for tomorrow’s trends and technologies, however, this can be expensive and not all companies and corporations are willing to spend their training budget in this manner.  At the very least you should keep yourself up to date with the current market direction to ensure that you do well in your CCNA career.  For example, it’s likely that areas like cloud computing and media convergence will become increasingly important over the next few years and these are heavily dependent on network technology.

Hope this helps!

Cheers,
Francis (SavvyNetCert.Com)

P.S. If you’re still preparing for your CCNA exam, using CCNA video training packages are a great way to study.  Do check out our comparison between the 2 best CCNA Video Training packages now.  Click here to find out more!

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Tips On Getting That First CCNA Job

Becoming a good CCNA network engineer and getting that first elusive CCNA job is definitely not an easy task, especially in this competitive job market.  Here are 2 tips to help you succeed in your CCNA career journey.

1. Get the CCNA

Despite Cisco’s introduction of the CCENT certification (which you will get after passing the ICND1 exam), the CCNA is still widely regarded as the must have basic network certification by the industry as a whole.  Thus, it is essential that you start working towards the CCNA certification as soon as possible.  It has been shown in many surveys (including the TCPmag Salary Survey) that certified networking professionals are paid more.  In this difficult market, being certified means that you have a better stab at that networking job.  I previously made 2 introductory posts on the CCNA which you should review for more details on the CCNA journey.  You might also want to take a look at CCNA video training which is an excellent way to get started.

2. Getting That First Networking CCNA Job

Once you have your CCNA, you can start looking for a suitable networking position.  However, even if you haven’t gotten the certification yet, some employers might still be willing to employ you based on other factors.  For example, if you are a CCENT certified and have relevant experience in other related fields such as servers, operating systems or general IT support, you might be considered favorably.  Other networking certifications such as the CompTia Network+ certification (which is vendor independent) might also carry some weight.

One thing you might want to note is that the people who write the job specifications on career websites, job boards or newspapers might not be the same people who are hiring.  Because of this, don’t always take the job requirements as set in stone and give it a shot anyway.  It is common that the person that is eventually hired might not fulfill all the requirements as employers usually put too wide a range of certifications required in the ad.

An impressive and professionally written resume also helps with getting that CCNA job.  You can do this yourself by reading some books or get a professional resume writer like those at ResumeWriters.Com (Tip: Use coupon code “newjob” at checkout for a 10% discount) for help.  Using a professional to get your resume done can improve your chances of getting an interview significantly.

Let me know if you enjoyed this post!  I can be contacted on twitter (@savvynetcert) or using the feedback form above.

Cheers,
Francis

P.S. If you are using a professional resume writer to get your resume done (recommended), don’t forget to claim your 10% discount at ResumeWriters.Com by using the coupon code “newjob” at checkout.

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