Networking Devices and Initial Configuration Module 10 – 12 Checkpoint Test Online

Hint

Cisco IOS uses different command modes for operational needs. The privileged EXEC mode is identified by a prompt that ends with the # symbol after the device name. The user EXEC mode is identified by a prompt that ends with the > symbol after the device name. The global configuration mode is identified by a prompt that ends with (config)# after the device name.

Hint

In order to enter global configuration mode, the command configure terminal, or a shortened version such as config t, must be entered from privileged EXEC mode. In this scenario the administrator is in user EXEC mode, as indicated by the > symbol after the hostname. The administrator would need to use the enable command to move into privileged EXEC mode before entering the configure terminal command.

Hint

The show interfaces command is useful to detect media errors, to see if packets are being sent and received, and to determine if any runts, giants, CRCs, interface resets, or other errors have occurred. The show ip interface command is useful in seeing whether the interface is “up and up”. The output of the show line command displays parameters for active lines that are in use such as the vty line used for Telnet. The show arp command shows the contents of the Address Resolution Protocol (ARP) table.

Hint

The IOS CLI provides hot keys and shortcuts that make configuring, monitoring, and troubleshooting easier. Some keys or key combinations shift between characters and entire commands. The tab key is used to complete a command that has been partially entered into the command line.

Hint

To interrupt an IOS process such as ping or traceroute, a user enters the Ctrl-Shift-6 key combination. Tab completes the remainder of parameters or arguments within a command. To exit from configuration mode to privileged mode use the Ctrl-Z keystroke. CTRL-R will redisplay the line just typed, thus making it easier for the user to press Enter and reissue the ping command.

Hint

An argument of a CLI command is generally not a predefined word, but rather is a value defined by the user. Keywords, however, describe specific parameters of a command that are predefined words that are known to the command interpreter.

Hint

In a routing table, the label C identifies a network that is directly connected to an interface on the device. This entry is added to the routing table when an interface is configured with an IP address and activated.

Hint

An SVI is a virtual interface and VLAN 1 is enabled by default on Cisco switches. VLAN 99 must be configured to be used. FastEthernet 0/1 and GigabitEthernet 0/1 are physical interfaces.

Hint

The startup-config and running-config files display most passwords in plaintext. Use the service password-encryption global config command to encrypt all plaintext passwords in these files.

Hint

In data communication, the default gateway device is involved only when a host needs to communicate with other hosts on another network. The default gateway address identifies a network device used by hosts to communicate with devices on remote networks. The IP address of the host and the default gateway address must be in the same network. With the default subnet mask, valid host IP addresses range from 128.107.0.1 to 128.107.255.254.

Hint

SSH is automatically enabled after the RSA keys are generated. Setting user privilege levels and configuring role-based CLI access are good security practices but are not a requirement of implementing SSH.

Hint

Place the options in the following order:

service password-encryption	R1(config)#
enable	R1>
copy running-config startup-config	R1#
login	R1(config-line)#
ip address 192.168.4.4 255.255.255.0	R1(config-if)#

Hint

Access to the VTY and console interfaces can be restricted using passwords. Out-of-band management of the router can be restricted in both user EXEC and privileged EXEC modes.

Hint

Place the options in the following order:

enable password	limits access to the privileged EXEC mode
vty password	limits access to the device through an SSH connection
console password	limits access to the device through an out-of-band connection
enable secret	encrypted and restricts access to the privileged EXEC mode

Hint

The purpose of ICMP messages is to provide feedback about issues that are related to the processing of IP packets.

Hint

Using the ipv6config command on PC2 displays the IPv6 address of PC2, which is 2001:DB8:1:4::A. The IPV6 link-local address, FE80::260:70FF:FE34:6930, is not used in route tracing. Using the tracert 2001:DB8:1:4::A command on PC1 displays four addresses: 2001:DB8:1:1::1, 2001:DB8:1:2::1 , 2001:DB8:1:3::2, and 2001:DB8:1:4::A.

Hint

The ping 127.0.0.1 command is used to verify that the TCP/IP stack is functional. It verifies the proper operation of the protocol stack from the network layer to physical layer, without sending a signal on the media. That is, this test does not go beyond the PC itself. For example, it does not detect whether a cable is connected to the PC or not.

Hint

ICMP is used by network devices to send error messages.

Hint

When a host or gateway receives a packet that it cannot deliver, it can use an ICMP Destination Unreachable message to notify the source that the destination or service is unreachable. The message will include a code that indicates why the packet could not be delivered. These are some of the Destination Unreachable codes for ICMPv4: 0 : net unreachable 1 : host unreachable 2 : protocol unreachable 3 : port unreachable

Hint

ICMPv6 uses the hop limit field in the IPv6 packet header to determine if the packet has expired. If the hop limit field has reached zero, a router will send a time exceeded message back towards the source indicating that the router cannot forward the packet.

Hint

The ping command can be used to test end-to-end connectivity between two host devices. It measures the round-trip time for a message to get from source to destination.

Hint

SSH provides a secure remote login through a virtual interface. SSH provides a stronger password authentication than Telnet. SSH also encrypts the data during the session.

Hint

Traceroute progressively increments the TTL (IPv4) or hop limit (IPv6) field (1, 2, 3, 4…) for sending sequence of ping commands. When a router senses that the TTL or hop limit is 0, it will discard the packet and send a time exceeded message to the source of the traceroute. The returned message contains the IP address of the router that discarded the packet. Hence the traceroute utility learns the address of the router. This process continues and provides the trace with the address of each hop (router) as the packets continue traveling through routers to reach the destination.