The Dynamic Host Configuration Protocol (DHCP) protocol allows DHCP Clients to lease an IP address from a DHCP server. Simple enough. However, the protocol itself is open to various cybersecurity [...]
While most router interfaces use configured IP addresses, in some cases, a design calls for the router to dynamically learn an interface IP address. In those cases, routers can be configured to [...]
Most DHCP servers sit in a centralized location. To make that work, routers need to participate in the DHCP process to a small degree using a feature called the DHCP Relay Agent. For this lab, [...]
The Cisco switch Port Security feature lets the switch monitor incoming frames, look at the source MAC address, and determine whether frames with that source address should or should not be [...]
Sometimes, #CCNA studiers get bogged down with port security, focusing on all those little optional configuration settings. But what of the main feature: securing the port? This latest lab [...]
Quick, can you name all the small options available with Cisco’s port security feature on Catalyst IOS images? Most of us can’t, unless we’re in the middle of studying for CCENT, [...]
Cisco’s Port Security feature just happens to be one of those switch features that can confuse people until they’ve configured and tested it a few times. One challenge comes from the fact that [...]
Are you comfortable matching packets with extended ACLs? How about with TCP and UDP ports in those ACLs? Here’s a 10-minute lab exercise to practice; all you need is the time and a piece of paper [...]
Ready to review how to match subnets with extended ACLs? And how to match well-known ports? Today’s lab lets you do just that. Along the way, you get to think about where to place the ACL to most [...]
Standard named ACLs follow a nice simple format, which is great for getting started with ACLs. This next lab gives you some exercise on the basic syntax, while throwing in a few issues related to [...]
Write a 1-line ACL to match something? Easy. Write a several line ACL with a bunch of requirements? A little harder. Choosing where to put that multi-line ACL, when the ACL requirements span [...]
This latest config lab takes a backwards approach to configuration. In this case, it starts with a bunch of show commands, and asks you to derive some of the key configuration items on several [...]
This latest config lab takes a backwards approach to configuration. In this case, it starts with a bunch of show commands, and asks you to derive some of the key configuration items on several [...]
IPv6 routing has many similarities with IPv4 routing; however, the length of the IPv6 addresses can sometimes get in the way of learning the main concepts. This next lab removes those barriers [...]
Ever get tired of sifting through the details of seemingly random IPv6 addresses? Well, today’s lab gives you yet another quick config exercise while using very easy-to-remember IPv6 addresses [...]
IPv6 addresses just take a little getting used to. This next lab gives you same reps with configuring Global Unicast addresses, while giving you a few mind-bending exercises to make you think [...]
Do you know how to take an interface MAC address and determine what IPv6 address the interface would use when using EUI-64? Could you then do the reverse: take the IPv6 address, and predict what [...]
OSPF chooses the best route to reach a subnet based on the lowest cost among all possible routes. OSPF calculates the cost as the sum of the OSPF interface costs of all outgoing interfaces in the [...]
OSPF uses a router’s Router ID (RID) to identify each router. We see the RID in many OSPF verification commands, so using predictable, known OSPF RID values can help people operate [...]
The OSPF network type setting happens to be one of the more useful optional OSPF features. This setting changes a couple of details about how OSPF operates on an interface. Ethernet WAN links [...]
OSPF includes many optional features. Depending on the network, particularly the WAN, you may ignore some of those features while possibly using others. The choice to influence which router [...]
A router configuration can enable OSPF on an interface directly using the ip ospf interface subcommand. In fact, the configuration is more direct and obvious than the old traditional use of the [...]
When using the OSPF network command, whether single area of multi-area, you have to be careful with the wildcard mask used and which interfaces each network command matches. With multiple areas, [...]
What if your #CCNA exam required you to configure the OSPF network command with a particular style of mask? What if it said “match all addresses in the subnet”, or “match all addresses in the [...]
The OSPF network command can cause a bit of mental trouble for anyone just starting out. The reason: the first two parameters require us to do a little math, compare that result to the router’s [...]