Getting Started Part 4: Simulators vs Real Gear for CLI Skills

Are Simulators Good Enough to Help You Pass CCNA?

You need CLI hands-on experience to do well on the Cisco CCENT and CCNA exams. To get that experience, you can use real routers and switches, a simulator that simulates routers and switches, or an emulator that emulates routers and switches. Today we'll take a closer look at Simulators, and compare that to the real gear option, as described in my previous post in this series. Next post, I'll have the space to hit the third option, emulators, and compare all three. As with the entire series, I'm writing the CCENT and CCNA newbies, but asking for more experienced folk to weigh in, particularly for the question of whether you can learn all you need about the CLI using a simulator, and a simulator only.

I'll go ahead and ask the question of the experienced folks, but feel free to read the whole post before choosing.

Defining "Simulator", in Context

The word "Simulator" can mean a lot of different things, so we need to agree on a definition that works in this context. For our purposes, a simulator is software that acts like the Cisco CLI. The software runs on commonly-used Operating Systems. All you need is the simulator software - you don't need any router or switch hardware, and you don't need a copy of Cisco IOS. So, if you compare the real gear model, in which IOS supplies the CLI, and IOS runs on real hardware, to the Simulator model, you don't need real hardware or the real IOS.

The people that create any simulator have to work to reverse-engineer how the CLI works, and how routers and switches work. They have to decide which CLI commands, and which command parameters, to support. They have to decide how the devices work under countless combinations of configuration commands, and in different topologies of devices and connections. Because of the large number of combinations of commands, command parameters, and configuration combinations, most simulators have at least some differences when compared to how real gear works, with real IOS, under those same conditions.

Simulators also come in many flavors. Some simply check the command syntax of what you type, but the show commands, that list device status info, do not list meaningful info. Others may let you configure something, and display correct show command output - but only if you strictly follow a series of lab steps. Others may let you either follow the lab or deviate, and display realistic output regardless. Some even let you define the topology, while others let you use only the topologies provided by the software.

Top Simulators

As for actual products, you can as usual Google to find a longer list. It is not my intent to omit any particular product, or emphasize any product. However, if you combine the most popular hits from Amazon and from searching the Cisco Learning Network (CLN), four Sim products stand out just in terms of the volume of mentions and listings. So I'll list these products for examples.

Of these, all have CCNA versions, all support a large percentage of CCNA-level commands, and all allow you to either follow the lab steps or deviate. The first three in the list also let you create your own topologies. The list below gives links, and a few differentiators.

  • Boson NetSim - Comercially available; been in the business a while; CCNA and CCNP versions; sold at
  • CCNA Virtual Lab - Commercially available; been in the business a while; CCNA and CCNP versions; available at
  • PacketTracer - Written by Cisco for Cisco Networking Academy (CNA);  supports CCNA and CCNP features; licensed to CNA students/teachers only
  • Pearson CCNA Network Simulator - Relative newcomer (last few years); CCENT and CCNA versions; no user ability to change the topology; lots of labs; Wendell gets paid (disclaimer)

To wrap up the Simulator overview, let me ramble a bit. First, I do not intend to give a complete list of differentiating features, make a claim who is best, etc. Second, I get paid on the last one, because I wrote some labs, edited others, helped design it, etc, so you should take that into consideration as well. So, you have work to do to compare these if you're interested. Also, of these four, Packet Tracer is the oddest of all in terms of comparison, in that it is 1) free and 2) Cisco restricts it's use to those taking a Cisco Networking Academy course. But if taking a CNA course, you'd be crazy not to get it and use it.

Simulators vs Real

As you start working towards CCENT and CCNA, you will need to make a choice about how to get your CLI experience: real, simulator, or emulator. I've collected some of the key decision points between the years on my web site, for reference. But let's take this last part of today's discussion to look at a few of the most important points.

Effectiveness of Learning for CCENT and CCNA

First off, many people ask the question of whether you can learn enough to pass the exams using a simulator, and no real gear. This is my opinion, but the answer is yes. (That was also my opinion before I started getting paid for a Sim, by the way.) It depends on the Sim - the software, the quality of its support for various commands, its labs, the lab descriptions that help you learn, and so on - but they are often designed to help you learn for the exams, so Sims can be very effective.

However, there is a difference between what you can learn with real gear and Simulators. With real gear, you get to connect real cables, see the interfaces, see the actual console messages when the routers boot, experience software upgrades more realistically, and a few other things that you just can't get with a simulator. However, the exam itself uses a simulator - a simulator Cisco creates for the exam and doesn't sell or release outside the company. As long as the simulator you use is good - supports the commands, gives realistic output, and so on - you can certainly learn plenty to pass.


I plan a reprise on my CCNA lab series this spring, including updating prices for some sample topologies. However, in the mean time, to get a general idea, you can build a minimal CCNA topology with 2 routers for a little under $100 US, if you live here in the US. You can build a 2-router/1-switch topology for say $150-$200. You'd be well set for CCNA investing $300-$400.

The simulators vary in price, but even the more expensive CCNA simulators run around $200-$400. The Pearson simulator runs around $100 actual price. And Packet Tracer is free - only problem is that while you can probably find a place to download it even if you're not in a CNA course, that breaks Cisco's license for its use.

Benefits to Real Jobs

At some point, you need to be able to do a job that requires these CLI skills. Learning on real gear does give you an advantage there compared to Simulators. You can always plan on getting your CCENT and/or CCNA with a simulator, and then getting access to real gear at the next job, but I'd have to say that real gear wins this battle.

Time between Choosing and Effective Learning for the Exam

Say you choose, right now, to use real gear, and you've just started studying for the ICND1 exam. You have a small learning curve. What gear to buy? Cables? Where to buy? Should I buy a package from my cousin Vinnie, or from a reseller, or buy it piecemeal on EBay? Am I buying something useful, or will I waste a few hundred $ before I figure out what to get?

Compare that to Simulators. Once you choose to use a Simulator, it takes little time to be productive and learn. Especially if you buy a downloaded version, you could literally be learning the CLI withing 15 minutes. And you spend less electricity as compared with turning on several routers and switches.

Clearly, simulators win this comparison - but I'm a big fan of using real gear at this point in your study. Even if you just buy a pair of really old, really cheap 2501 routers, and a few cables, to do some learning on real gear, I think it's worth the time and expense. In fact, most people that work through the point of completing CCNP use at least two of the three options: real, simulators, and emulators. I think more light bulbs go off over your head using the real gear, and it helps for real life. So, maybe start with a small amount of real gear, and either a Sim or Emulator.

How Close is it to the Real Thing?

Well, real gear is easy - it is the real thing. It's real hardware, real IOS.

Simulators, at least as a class of product, cannot match the realism of real IOS running on real hardware. They can come close, and that closeness to the real IOS feeds into the perception of the competing products. However, none of them run real IOS under the covers, so some human must look at all the commands, parameters, apply their knowledge to predict what the command output should be in every case.


This figure summarizes some of the key pros and cons about whether to use a Simulator.

So, experienced folks, tell me your opinion: can CCENT or CCNA candidate learn plenty CLI to pass the test, using only a Simulator? What advice would you give on the Simulator front? And newbies, what questions do you have on the Simulator vs Real choice?

Related Posts: 

So You Want to Get STarted in Cisco Certs - Now What?

Getting Started Part 2: Primary CCNA Study Source

Getting Started, Part 3: What and Why on the Cisco CLI

Getting Started, Part 3: What and Why on the Cisco CLI

What to Consider After PAssing CCNA

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