Introduction

There is no doubt that one of the most important parts of the CCNA Routing and Switching exam is the coverage of routing technologies. A network technician will encounter routing tasks in even a small network; therefore, he or she must have good knowledge about static and dynamic routing and the operation of routers.

What Percentage of the Exam Covers Routing Technologies?

You can expect many questions from this topic on the exam. According to the official documentation, questions from the routing technologies take 23% of the entire exam. That means that almost every fourth question (namely, if the exam consists of 70 questions, then 16-17 of them) is about routing.

What Topics Are Covered in This Section of the Exam?

There are 14 subtopics within the main topic, and some of them are further subdivided. If we try to reduce the number, we can say that a CCNA candidate must know about the theory of routing, the packages, static and dynamic routing and troubleshooting. More precisely, the main topics are:

  1. Describe the routing concepts and interpret the components of a routing table
  2. Compare and contrast static and dynamic routing, distance vector and link state routing protocols
  3. Configure, verify, and troubleshoot IPv4/IPv6 static routing and inter-VLAN routing
  4. Configure, verify, and troubleshoot single area and multi-area OSPFv2/v3, EIGRP for IPv4/IPv6 and RIPv2 for IPv4
  5. Troubleshoot basic Layer 3 end-to-end connectivity issues

High-Level Overview of Routing Technologies Topics

Let’s look at these subtopics in more detail.

Describe the routing concepts and interpret the components of a routing table

Although practice is very important for a network technician, it’s also important to know the theory behind the routing of packets through the network. It means that, first of all, you will need to know the important parts of the IP packet header (at least the source and destination address and the TTL field), as well as the Ethernet frame structure. This is because you can expect questions about packet handling along the path from the source to the destination, including frame rewrite and routing decisions based on the routing table. Although modern routers use Cisco Express Forwarding (CEF), you don’t need a thorough understanding of this technology, just the good old method of routing.

The routing table is the main database of a router, so you must know its components and how this data can be used by the router. You need to be aware of the following concepts: prefix, network mask, next hop, metric and gateway of last resort. Moreover, because Cisco routers use the concept of administrative distance to distinguish various routing sources, you need to memorize the values associated with them. For example, if you have to configure a floating static route, which can be a backup route instead of a dynamically learned one, you need to know the admin distance of that dynamic protocol.

Compare and contrast static and dynamic routing, distance vector and link state routing protocols

There are various methods for a router to determine the path for a destination network. Some exam questions could be about the advantages and disadvantages of static routing as compared with dynamic routing. For example, there might be a question about choosing the routing method in a network, and you need to know where and when to use static instead of dynamic routing.

First, you need to classify dynamic routing protocols as interior and exterior. Although BGP is mentioned in the CCNA study, the main emphasis is on the interior protocols. Second, you need to know the theory behind distance vector and link-state protocols, including the principles of how they work, how they treat neighbor routers, what kind of information they share, and how they build the routing table. The two important routing protocols you need to concentrate on are OSPF and EIGRP, but RIP is also still here as a pure distance-vector protocol. Although its role is getting smaller in modern networks, we should learn a bit about it in order to have a completely successful exam.

Configure, verify and troubleshoot IPv4/IPv6 static routing and inter-VLAN routing

The following topics are for those who prefer practice over theory. The first big part is the configuration of static routing. You need to know the usable methods: setting a route with next hop, outgoing interface or both. Knowing how to set up a default route in either an IPv4 or IPv6 network is also mandatory.

Besides network routes, you need to know about host routes. As mentioned before, there exists a special static route, the floating one, which can be an alternate or backup route; it is usually used along with a dynamic protocol.

Last but not least, we have inter-VLAN routing: You need to know the subinterface method as well as routing with switch virtual interfaces (SVIs).

In addition to the configuration, verification is also important. The network technician needs to be familiar with the software tools (ping, traceroute) and IOS commands used to test the operation of the routers and the configured routes.

Finally, when an error occurs, you have to find the cause as quickly as possible and fix the error. This needs a lot of practice: You need to know how to display the proper information and understand it. For example, there might be a question which shows you an output from a command and you have to deduce the reason for the error from it.

Configure, verify and troubleshoot single area and multi-area OSPFv2/v3, EIGRP for IPv4/IPv6, and RIPv2 for IPv4

Configuring dynamic routing protocols is usually more difficult than static routes and requires more knowledge. On the exam, you will need to know RIPv2, OSPFv2 and EIGRP for IPv4, as well as OSPFv3 and EIGRP for IPv6. Beyond the basic configuration, there are specialties: for example, distributing a default route or manipulating path cost. It’s important to mention that the official documentation excludes some areas of configuration for each of the protocols (such as authentication, filtering, manual summarization and some others) for each of the protocols, which makes our life a bit easier.

Verifying and troubleshooting a network using a dynamic protocol can be a challenge, so I repeat my advice: Practice a lot before the exam! The optimal way is to use real gear, but at the CCNA level, Packet Tracer is enough.

Troubleshoot basic Layer 3 end-to-end connectivity issues

During the operations of a network, there will definitely be some errors and malfunctions you have to fix. Some troubleshooting skills will be needed for a successful exam result. You need to know the software tools that can help identify the problem, and you need to understand the output of the related “show” commands to deduce the reason for an error. Usage of ping and traceroute (also on end devices) is important because they are the basic testing tools of end-to-end connectivity. The knowledge of basic “debug” commands is also essential.

These types of questions on the exam require the ability to notice small pieces of information: a missing or badly advertised network, a non-matching AS number or timer, and so on. You will need to know what the correct configuration should look like, and how you can fix a bad one. In my opinion, troubleshooting is the most challenging type of exam question.

Where Should I Focus My Study Time?

One cannot have a successful CCNA exam without practicing configuration and troubleshooting. Because routing is the most weighty part of the exam (if we look at the percent of questions), this sentence is even more important. My advice is to do as many labs as you can, If possible, on real devices, but using Packet Tracer is fine at this level. You can also find many downloadable lab files on the Internet!

Try to experiment with the configuration by making errors intentionally and watch the result; this can be a good basis for troubleshooting skills. Try to memorize the output of the relevant “show” commands (for example, show IP/IPV6 protocols and show running-config). Try to think just like the router: Take a package and follow its path from the source to the destination. Packet Tracer is an ideal tool for this, using the Simulation Mode. If you can access real devices, then use Wireshark: it’s the best tool for keeping track of and understanding the conversation between dynamic routing protocols.

Conclusion

Routing in a network is an essential technology that every CCNA candidate needs to know thoroughly. The main topics on the exam in this field are mostly practical, such as configuring and troubleshooting static routing and dynamic protocols. But, of course, understanding the theory behind all of this is also important! Without it, you cannot understand the operation of a router and cannot configure it to choose the best path for the packets.

 

Sources

CCNA Exam Topics, Cisco Learning Network

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