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Showing posts from August 7, 2009

CCNA v4 - E2 - Module 5 (100/100)

1. Refer to the exhibit. All routers in the exhibit are running RIP v1. The network administrator issues the show ip route command on router A. What routes would appear in the routing table output if the network is converged? (Choose two).   R 192.168.2.0/24 [120/1]   R 10.10.1.0/24 [120/2] 2. Refer to the exhibit. The Ethernet interface on Router2 goes down and the administrator notices that the route is still valid in the routing table of Router1. How much longer will it take for Router1 to mark the route invalid by setting the metric to 16?   155 seconds 3. Refer to the exhibit. The network that is shown is running RIPv1. The 192.168.10.0/24 network was recently added and will only contain end users. What command or set of commands should be entered on Router1 to prevent RIPv1 updates from being sent to the end user devices on the new network while still allowing this new network to be advertised to other routers?   Router1(config-router)# passive-interface fastethernet 0/0 4. Which

CCNA v4 - E2 - Module 4 (100/100)

1. A network administrator is evaluating RIP versus EIGRP for a new network. The network will be sensitive to congestion and must respond quickly to topology changes. What are two good reasons to choose EIGRP instead of RIP in this case? (Choose two.)   EIGRP only updates affected neighbors.   EIGRP updates are partial. 2. Which event will cause a triggered update?   a route is installed in the routing table 3. Refer to the exhibit. If all routers are using RIP, how many rounds of updates will occur before all routers know all networks?   3 4. Refer to the exhibit. The routers in this network are running RIP. Router A has not received an update from Router B in over three minutes. How will Router A respond?   The Invalid timer will mark the route as unusable if an update has not been received in 180 seconds. 5. The graphic shows a network that is configured to use RIP routing protocol. Router2 detects that the link to Router1 has gone down. It then advertises the network for this link

How the Application Layer Works

In the previous section we reviewed several aspects of the Transport Layer. We learned a great deal of information; covering sockets, ports, TCP, UDP, segments, and datagrams. Now we will take a look at the fourth and final layer of the TCP/IP stack: the Application Layer. What Does The Application Layer Do? A lot of newcomers to TCP/IP wonder why an Application Layer is needed, since the Transport Layer handles a lot of interfacing between the network and applications. While this is true, the Application Layer focuses more on network services, APIs, utilities, and operating system environments. If you know the TCP/IP stack and OSI model well enough, you’ll know that there are three OSI model layers that correspond to the TCP/IP Application Layer. By breaking the TCP/IP Application Layer into three separate layers, we can better understand what responsibilities the Application Layer actually has. The OSI Equivalent of the TCP/IP Application Layer 1. Application Layer - The sev

Enable Passwords On Cisco Routers Via Enable Password And Enable Secret

Security is a part of every good technical administrator’s game plan. Luckily the good folks at Cisco have made the task of securitizing a Cisco router fairly straightforward in design- with support given for up to five types of passwords. Taking advantage of these passwords is vital to a network’s internal security, and should be implemented where permitted. Enable Password – The Most Basic Of Security Features The two most basic of passwords a Cisco router can provide support for is the enable password and enable secret commands. Depending on the IOS version, administrators will likely only need to setup the enable secret command. For Cisco routers running IOS versions before version 10.3, enable password is going to be used. It is the outdated version of the two, and we’ll see why it isn’t used in average applications after we enable it. You can enable this basic password following the commands seen below. Router> enable Router# config terminal Enter configuration co

The Basics of Network Cable Testing

If 90% of all problems in a network are on the Physical Layer, then it isn’t any surprise that cable testing has become quite important in the industry. And although it may sound simple to test a pair of cables for faults, actually troubleshooting wire maps, crosstalk, propagation delay, or insertion loss can be more than headache-worthy. And thus, understanding how to troubleshoot these problems saves time, yet also supplies good information to prevent common mistakes in the future. How to Avoid Crosstalk You’ll come to find that the most common mistakes are usually the simplest to avoid. For instance, crosstalk is very commonly created when connectors are not installed properly at both ends of the cable. Crosstalk is the effect we get when electromagnetic energy from one cable leaves an imprint on adjacent cables. (You’ll often see this referred to as “noise.”)This usually isn’t a problem, however, since we twist wires inside Ethernet cable to cancel out this effect. So how, t