ICND1 | Interconnecting Cisco Networking Devices 1

On a computer with the Microsoft Windows operating system, the ipconfig command can be used to display all current TCP/IP network configuration values at the command line. Using various parameters, the command can also be used to refresh DHCP and DNS settings. The /release parameter sends a DHCPRELEASE message to the DHCP server. This will release the current DHCP configuration and discard the IP address configuration for all of the adapters that are configured to obtain an IP address automatically. The /renew parameter renews the DHCP configuration for all of the adapters that are configured to obtain an IP address automatically.

The other commands will not refresh the DHCP configuration.
On a computer with the Microsoft Windows operating system, the ipconfig command can be used to display all current TCP/IP network configuration values at the command line. Using various parameters, the command can also be used to refresh DHCP and DNS settings. The /release parameter sends a DHCPRELEASE message to the DHCP server. This will release the current DHCP configuration and discard the IP address configuration for all of the adapters that are configured to obtain an IP address automatically. The /renew parameter renews the DHCP configuration for all of the adapters that are configured to obtain an IP address automatically.

The other commands will not refresh the DHCP configuration.
On a computer with the Microsoft Windows operating system, the ipconfig command can be used to display all current TCP/IP network configuration values at the command line. Using various parameters, the command can also be used to refresh DHCP and DNS settings. The /release parameter sends a DHCPRELEASE message to the DHCP server. This will release the current DHCP configuration and discard the IP address configuration for all of the adapters that are configured to obtain an IP address automatically. The /renew parameter renews the DHCP configuration for all of the adapters that are configured to obtain an IP address automatically.

The other commands will not refresh the DHCP configuration.

To permit the discovery of non-Cisco devices, Cisco switches support Link Layer Discovery Protocol (LLDP), which is a vendor-neutral device discovery protocol that IEEE 802.1AB standard defines. LLDP allows network devices to advertise information about themselves to other devices on the network. This protocol runs over the data link layer, which allows two systems that are running different network layer protocols to learn about each other. To enable LLDP globally on a Cisco device, use the lldp run command.

After you globally enable LLDP, it is enabled on all supported interfaces by default. The lldp transmit command enables the transmission of LLDP packets on an interface. The lldp receive command enables the reception of LLDP packets on an interface.

CDP is primarily used to obtain protocol addresses of neighboring Cisco devices and discover the platform of those devices
To permit the discovery of non-Cisco devices, Cisco switches support Link Layer Discovery Protocol (LLDP), which is a vendor-neutral device discovery protocol that IEEE 802.1AB standard defines. LLDP allows network devices to advertise information about themselves to other devices on the network. This protocol runs over the data link layer, which allows two systems that are running different network layer protocols to learn about each other. To enable LLDP globally on a Cisco device, use the lldp run command.

After you globally enable LLDP, it is enabled on all supported interfaces by default. The lldp transmit command enables the transmission of LLDP packets on an interface. The lldp receive command enables the reception of LLDP packets on an interface.

CDP is primarily used to obtain protocol addresses of neighboring Cisco devices and discover the platform of those devices
To permit the discovery of non-Cisco devices, Cisco switches support Link Layer Discovery Protocol (LLDP), which is a vendor-neutral device discovery protocol that IEEE 802.1AB standard defines. LLDP allows network devices to advertise information about themselves to other devices on the network. This protocol runs over the data link layer, which allows two systems that are running different network layer protocols to learn about each other. To enable LLDP globally on a Cisco device, use the lldp run command.

After you globally enable LLDP, it is enabled on all supported interfaces by default. The lldp transmit command enables the transmission of LLDP packets on an interface. The lldp receive command enables the reception of LLDP packets on an interface.

CDP is primarily used to obtain protocol addresses of neighboring Cisco devices and discover the platform of those devices

When the IP packet travels across the network topology as shown in the exhibit, it will be manipulated by the devices and changed based on the interfaces information. The layer 3 header is made up of the source and destination IP addresses, which do not change. However the source and destination MAC addresses in the layer 2 header will change.

When a packet leaves Router B, the source MAC address will be that of Fa0/0. Its source and destination IP address will be 10.3.3.2 and 10.2.2.2 respectively.

A MAC address is an Ethernet technology, therefore a serial port would not have a MAC address.
When the IP packet travels across the network topology as shown in the exhibit, it will be manipulated by the devices and changed based on the interfaces information. The layer 3 header is made up of the source and destination IP addresses, which do not change. However the source and destination MAC addresses in the layer 2 header will change.

When a packet leaves Router B, the source MAC address will be that of Fa0/0. Its source and destination IP address will be 10.3.3.2 and 10.2.2.2 respectively.

A MAC address is an Ethernet technology, therefore a serial port would not have a MAC address.
When the IP packet travels across the network topology as shown in the exhibit, it will be manipulated by the devices and changed based on the interfaces information. The layer 3 header is made up of the source and destination IP addresses, which do not change. However the source and destination MAC addresses in the layer 2 header will change.

When a packet leaves Router B, the source MAC address will be that of Fa0/0. Its source and destination IP address will be 10.3.3.2 and 10.2.2.2 respectively.

A MAC address is an Ethernet technology, therefore a serial port would not have a MAC address.

The dynamic learning port security method is used when you care only about how many MAC addresses are permitted to use the port, rather than which MAC addresses are permitted.If a port on which dynamic learning is configured has a link-down condition, all dynamically learned addresses are removed. Following bootup, a reload, or a link-down condition, port security does not populate the address table with dynamically learned MAC addresses until the port receives ingress traffic. Depending on how you configure the device, dynamically learned addresses age out after a certain period and new addresses are learned, up to the maximum that you have defined.

Sticky learning and Static learning would not be the best to use as you require dynamic learning of the MAC addresses, and you would like to clear the MAC table after five minutes. Static learning has the administrator manually input the MAC addresses. Sticky learning remembers the MAC addresses that are seen on the interface, and would not remove them after five minutes.
The dynamic learning port security method is used when you care only about how many MAC addresses are permitted to use the port, rather than which MAC addresses are permitted.If a port on which dynamic learning is configured has a link-down condition, all dynamically learned addresses are removed. Following bootup, a reload, or a link-down condition, port security does not populate the address table with dynamically learned MAC addresses until the port receives ingress traffic. Depending on how you configure the device, dynamically learned addresses age out after a certain period and new addresses are learned, up to the maximum that you have defined.

Sticky learning and Static learning would not be the best to use as you require dynamic learning of the MAC addresses, and you would like to clear the MAC table after five minutes. Static learning has the administrator manually input the MAC addresses. Sticky learning remembers the MAC addresses that are seen on the interface, and would not remove them after five minutes.
The dynamic learning port security method is used when you care only about how many MAC addresses are permitted to use the port, rather than which MAC addresses are permitted.If a port on which dynamic learning is configured has a link-down condition, all dynamically learned addresses are removed. Following bootup, a reload, or a link-down condition, port security does not populate the address table with dynamically learned MAC addresses until the port receives ingress traffic. Depending on how you configure the device, dynamically learned addresses age out after a certain period and new addresses are learned, up to the maximum that you have defined.

Sticky learning and Static learning would not be the best to use as you require dynamic learning of the MAC addresses, and you would like to clear the MAC table after five minutes. Static learning has the administrator manually input the MAC addresses. Sticky learning remembers the MAC addresses that are seen on the interface, and would not remove them after five minutes.

The restrict violation mode also drops packets with unknown source addresses until you remove enough secure MAC addresses to drop below the maximum value. However, it also generates a log message and causes the security violation counter to increment.

The protect violation mode drops packets with unknown source addresses until you remove enough secure MAC addresses to drop below the maximum value. It does not keep a running count of packets dropped. The shutdown violation mode puts the interface into an error-disabled state immediately. Error-disabled is not a port violation mode, but a state that is caused from the shutdown violation mode.
The restrict violation mode also drops packets with unknown source addresses until you remove enough secure MAC addresses to drop below the maximum value. However, it also generates a log message and causes the security violation counter to increment.

The protect violation mode drops packets with unknown source addresses until you remove enough secure MAC addresses to drop below the maximum value. It does not keep a running count of packets dropped. The shutdown violation mode puts the interface into an error-disabled state immediately. Error-disabled is not a port violation mode, but a state that is caused from the shutdown violation mode.
The restrict violation mode also drops packets with unknown source addresses until you remove enough secure MAC addresses to drop below the maximum value. However, it also generates a log message and causes the security violation counter to increment.

The protect violation mode drops packets with unknown source addresses until you remove enough secure MAC addresses to drop below the maximum value. It does not keep a running count of packets dropped. The shutdown violation mode puts the interface into an error-disabled state immediately. Error-disabled is not a port violation mode, but a state that is caused from the shutdown violation mode.

A Cisco router is not capable of negotiating a trunking protocol through use of the dynamic trunking protocol. The switch must be configured explicitly with a trunking protocol. In this case, the switchport mode trunk command enables the 802.1q trunking protocol.

The switchport mode dynamic auto command will not resolve the trunk establishment issue. This command is used to auto negotiate trunking protocols by using the dynamic trunking protocol.
A Cisco router is not capable of negotiating a trunking protocol through use of the dynamic trunking protocol. The switch must be configured explicitly with a trunking protocol. In this case, the switchport mode trunk command enables the 802.1q trunking protocol.

The switchport mode dynamic auto command will not resolve the trunk establishment issue. This command is used to auto negotiate trunking protocols by using the dynamic trunking protocol.
A Cisco router is not capable of negotiating a trunking protocol through use of the dynamic trunking protocol. The switch must be configured explicitly with a trunking protocol. In this case, the switchport mode trunk command enables the 802.1q trunking protocol.

The switchport mode dynamic auto command will not resolve the trunk establishment issue. This command is used to auto negotiate trunking protocols by using the dynamic trunking protocol.

When using the debug ip rip command, at first it seems like nothing is happening. However, if you wait a few seconds, you will be presented with output such as the one in the |h %5coutput%5ct10%5cmisc%5c100105eo326a.html exhibit.

This command will show you any time a RIPv2 update comes in to update the routing table, or anytime the device you entered the command on sends an update out. When an update is sent, the update is sent out as a broadcast (255.255.255.255) and the output will tell you on which interface the update has been sent and what the update contains. For an example of output presented when sending an update, refer to the |h %5coutput%5ct10%5cmisc%5c100105eo326b.html exhibit.

A device's startup-config is stored in the NVRAM, whereas the running-config is saved in RAM. In this example, we wish to move the contents of the startup-config in NVRAM to a TFTP server. The command to do this is copy startup-config tftp:.

The copy tftp: startup-config command would copy a file from the TFTP server to the device's startup-config in NVRAM. This is the reverse of what we wish to achieve in this scenario. A device's running-config is stored in RAM and the startup-config is saved in NVRAM. The copy running-config tftp: command is copying the contents of RAM, not NVRAM, to the TFTP server. The copy tftp: running-config command would copy a file from the TFTP server into the device's running-config in RAM. It would not back up a switch's NVRAM data to a server.

Passwords that are displayed or set after you configure the service password-encryption command will be encrypted. Service password encryption uses type-7 encryption, which is not very secure. This can be determined from the number seven after the word "password" in the syntax. Several tools and web pages available can convert an encrypted password into a plain text string.

The password is encrypted and 106D000A0618 is not the actual password. Since a username is present in the show run output, the enable secret command has not been used. This command is used to configure a password only, not a username and a password. The secret command applies a strong MD5 hash to passwords, and it is considered a type-5 encryption. This configuration is identified by the number 5 after the word "secret" in the command output.
Passwords that are displayed or set after you configure the service password-encryption command will be encrypted. Service password encryption uses type-7 encryption, which is not very secure. This can be determined from the number seven after the word "password" in the syntax. Several tools and web pages available can convert an encrypted password into a plain text string.

The password is encrypted and 106D000A0618 is not the actual password. Since a username is present in the show run output, the enable secret command has not been used. This command is used to configure a password only, not a username and a password. The secret command applies a strong MD5 hash to passwords, and it is considered a type-5 encryption. This configuration is identified by the number 5 after the word "secret" in the command output.
Passwords that are displayed or set after you configure the service password-encryption command will be encrypted. Service password encryption uses type-7 encryption, which is not very secure. This can be determined from the number seven after the word "password" in the syntax. Several tools and web pages available can convert an encrypted password into a plain text string.

The password is encrypted and 106D000A0618 is not the actual password. Since a username is present in the show run output, the enable secret command has not been used. This command is used to configure a password only, not a username and a password. The secret command applies a strong MD5 hash to passwords, and it is considered a type-5 encryption. This configuration is identified by the number 5 after the word "secret" in the command output.

The link layer from the TCP/IP stack maps to the physical and data-link layers from the OSI model. The physical layer defines the electrical, mechanical, procedural, and functional specifications for activating, maintaining, and deactivating the physical link for bit transmission between end devices. Protocols and services defined at this layer include Bluetooth, DSL, and USB. The data-link layer defines how data is formatted for transmission and how access to physical media is controlled. This layer typically includes error detection and correction to ensure reliable delivery of the data.

The network layer from the OSI model maps to the Internet layer from the TCP/IP Stack. The Internet layer is not part of the OSI model. It is a layer in the TCP/IP stack.
The link layer from the TCP/IP stack maps to the physical and data-link layers from the OSI model. The physical layer defines the electrical, mechanical, procedural, and functional specifications for activating, maintaining, and deactivating the physical link for bit transmission between end devices. Protocols and services defined at this layer include Bluetooth, DSL, and USB. The data-link layer defines how data is formatted for transmission and how access to physical media is controlled. This layer typically includes error detection and correction to ensure reliable delivery of the data.

The network layer from the OSI model maps to the Internet layer from the TCP/IP Stack. The Internet layer is not part of the OSI model. It is a layer in the TCP/IP stack.
The link layer from the TCP/IP stack maps to the physical and data-link layers from the OSI model. The physical layer defines the electrical, mechanical, procedural, and functional specifications for activating, maintaining, and deactivating the physical link for bit transmission between end devices. Protocols and services defined at this layer include Bluetooth, DSL, and USB. The data-link layer defines how data is formatted for transmission and how access to physical media is controlled. This layer typically includes error detection and correction to ensure reliable delivery of the data.

The network layer from the OSI model maps to the Internet layer from the TCP/IP Stack. The Internet layer is not part of the OSI model. It is a layer in the TCP/IP stack.

For a trunk link to be established, both ends of the trunk link must be configured to use the same native VLAN. Cisco Discovery Protocol (CDP) will present a native VLAN mismatch error message if the native VLANs do not match. To display the status of the trunk and the native VLAN used on that trunk link, and to verify trunk establishment, you can use the show interface trunk command in privileged EXEC mode.

Cisco Discovery Protocol (CDP) exchanges hardware and software device information with its directly connected CDP neighbors. Although this is a useful troubleshooting tool, it would not prevent hosts from communicating with each other. Dynamic Trunking Protocol (DTP) is a Cisco proprietary protocol used to manage automatic trunk negotiation. Disabling DTP would create further issues, as the trunk link would be disabled. Disabling RSTP would not prevent hosts from communicating with each other unless there was a loop involved.
For a trunk link to be established, both ends of the trunk link must be configured to use the same native VLAN. Cisco Discovery Protocol (CDP) will present a native VLAN mismatch error message if the native VLANs do not match. To display the status of the trunk and the native VLAN used on that trunk link, and to verify trunk establishment, you can use the show interface trunk command in privileged EXEC mode.

Cisco Discovery Protocol (CDP) exchanges hardware and software device information with its directly connected CDP neighbors. Although this is a useful troubleshooting tool, it would not prevent hosts from communicating with each other. Dynamic Trunking Protocol (DTP) is a Cisco proprietary protocol used to manage automatic trunk negotiation. Disabling DTP would create further issues, as the trunk link would be disabled. Disabling RSTP would not prevent hosts from communicating with each other unless there was a loop involved.
For a trunk link to be established, both ends of the trunk link must be configured to use the same native VLAN. Cisco Discovery Protocol (CDP) will present a native VLAN mismatch error message if the native VLANs do not match. To display the status of the trunk and the native VLAN used on that trunk link, and to verify trunk establishment, you can use the show interface trunk command in privileged EXEC mode.

Cisco Discovery Protocol (CDP) exchanges hardware and software device information with its directly connected CDP neighbors. Although this is a useful troubleshooting tool, it would not prevent hosts from communicating with each other. Dynamic Trunking Protocol (DTP) is a Cisco proprietary protocol used to manage automatic trunk negotiation. Disabling DTP would create further issues, as the trunk link would be disabled. Disabling RSTP would not prevent hosts from communicating with each other unless there was a loop involved.

A default route can be used in situations where the route from a source to a destination is not known or when it is not feasible for the router to maintain many routes in its routing table. To configure a default route, you use the ip route command. You need to configure the default route on Router B, as this router needs to know where to forward the traffic. To configure a default route using the next-hop router, you would use the following command:
RouterB(config)#ip route 0.0.0.0 0.0.0.0 172.16.2.2

The ip route 0.0.0.0 0.0.0.0 172.16.2.1 command will not work, as it is not specifying the correct interface. It is using the IP address of its exit interface. When specifying the exit interface, you must use the interface name. The ip route 0.0.0.0 0.0.0.0 s/0/0/0 command will not work, as it is not specifying the correct exit interface. It is using the name of the exit interface for Router A, not Router B. The ip route 0.0.0.0 0.0.0.0 s0/0/1 command would work; however, it is being configured on the incorrect router.
A default route can be used in situations where the route from a source to a destination is not known or when it is not feasible for the router to maintain many routes in its routing table. To configure a default route, you use the ip route command. You need to configure the default route on Router B, as this router needs to know where to forward the traffic. To configure a default route using the next-hop router, you would use the following command:
RouterB(config)#ip route 0.0.0.0 0.0.0.0 172.16.2.2

The ip route 0.0.0.0 0.0.0.0 172.16.2.1 command will not work, as it is not specifying the correct interface. It is using the IP address of its exit interface. When specifying the exit interface, you must use the interface name. The ip route 0.0.0.0 0.0.0.0 s/0/0/0 command will not work, as it is not specifying the correct exit interface. It is using the name of the exit interface for Router A, not Router B. The ip route 0.0.0.0 0.0.0.0 s0/0/1 command would work; however, it is being configured on the incorrect router.
A default route can be used in situations where the route from a source to a destination is not known or when it is not feasible for the router to maintain many routes in its routing table. To configure a default route, you use the ip route command. You need to configure the default route on Router B, as this router needs to know where to forward the traffic. To configure a default route using the next-hop router, you would use the following command:
RouterB(config)#ip route 0.0.0.0 0.0.0.0 172.16.2.2

The ip route 0.0.0.0 0.0.0.0 172.16.2.1 command will not work, as it is not specifying the correct interface. It is using the IP address of its exit interface. When specifying the exit interface, you must use the interface name. The ip route 0.0.0.0 0.0.0.0 s/0/0/0 command will not work, as it is not specifying the correct exit interface. It is using the name of the exit interface for Router A, not Router B. The ip route 0.0.0.0 0.0.0.0 s0/0/1 command would work; however, it is being configured on the incorrect router.

To determine the best path to any given destination, routing protocols use a number that is called a metric. The metrics that the various routing protocols use differ, depending on the design of the routing algorithm that is used. The routing algorithm that the protocol uses generates a metric for each path through the network. Metrics can be based on a single characteristic or on several characteristics of a path. Sophisticated routing protocols can base route selection on multiple metrics, combining them into a single metric. Typically, the lower the metric value, the better the path.
To determine the best path to any given destination, routing protocols use a number that is called a metric. The metrics that the various routing protocols use differ, depending on the design of the routing algorithm that is used. The routing algorithm that the protocol uses generates a metric for each path through the network. Metrics can be based on a single characteristic or on several characteristics of a path. Sophisticated routing protocols can base route selection on multiple metrics, combining them into a single metric. Typically, the lower the metric value, the better the path.
To determine the best path to any given destination, routing protocols use a number that is called a metric. The metrics that the various routing protocols use differ, depending on the design of the routing algorithm that is used. The routing algorithm that the protocol uses generates a metric for each path through the network. Metrics can be based on a single characteristic or on several characteristics of a path. Sophisticated routing protocols can base route selection on multiple metrics, combining them into a single metric. Typically, the lower the metric value, the better the path.

A default route is an optional entry that is used when no explicit path to a destination is found in the routing table. This is also referred to as the gateway of last resort. The default route can be manually inserted or it can be populated from a dynamic routing protocol. The syntax for a default static route is the same as other static routes, except that the network address is 0.0.0.0 and the subnet mask is 0.0.0.0. Additionally, a default static route is identified by the letter "S" with an asterisk (*) for the code output. This makes default static routes easy to identify. A directly connected network is identified by the “C” code.
A default route is an optional entry that is used when no explicit path to a destination is found in the routing table. This is also referred to as the gateway of last resort. The default route can be manually inserted or it can be populated from a dynamic routing protocol. The syntax for a default static route is the same as other static routes, except that the network address is 0.0.0.0 and the subnet mask is 0.0.0.0. Additionally, a default static route is identified by the letter "S" with an asterisk (*) for the code output. This makes default static routes easy to identify. A directly connected network is identified by the “C” code.
A default route is an optional entry that is used when no explicit path to a destination is found in the routing table. This is also referred to as the gateway of last resort. The default route can be manually inserted or it can be populated from a dynamic routing protocol. The syntax for a default static route is the same as other static routes, except that the network address is 0.0.0.0 and the subnet mask is 0.0.0.0. Additionally, a default static route is identified by the letter "S" with an asterisk (*) for the code output. This makes default static routes easy to identify. A directly connected network is identified by the “C” code.

This configuration example demonstrates a dynamic Network Address Translation (NAT) configuration. Dynamic NAT maps an unregistered IPv4 address to a registered IPv4 address from a pool of registered IPv4 addresses (many-to-many). The example translates all source addresses that pass Access Control List (ACL) 1, which means a source address from the 192.168.1.0/24 network, into an address from the pool named net-208. The net-208 pool contains addresses from 171.69.233.209/28 to 171.69.233.222/28.

Because the "overload" keyword is missing from the command-line output PAT and NAT can be excluded as being possible correct options. Static NAT is a mapping of an unregistered IPv4 address to a registered IPv4 address on a one-to-one basis that does not involve an address pool as indicated in the output.
This configuration example demonstrates a dynamic Network Address Translation (NAT) configuration. Dynamic NAT maps an unregistered IPv4 address to a registered IPv4 address from a pool of registered IPv4 addresses (many-to-many). The example translates all source addresses that pass Access Control List (ACL) 1, which means a source address from the 192.168.1.0/24 network, into an address from the pool named net-208. The net-208 pool contains addresses from 171.69.233.209/28 to 171.69.233.222/28.

Because the "overload" keyword is missing from the command-line output PAT and NAT can be excluded as being possible correct options. Static NAT is a mapping of an unregistered IPv4 address to a registered IPv4 address on a one-to-one basis that does not involve an address pool as indicated in the output.
This configuration example demonstrates a dynamic Network Address Translation (NAT) configuration. Dynamic NAT maps an unregistered IPv4 address to a registered IPv4 address from a pool of registered IPv4 addresses (many-to-many). The example translates all source addresses that pass Access Control List (ACL) 1, which means a source address from the 192.168.1.0/24 network, into an address from the pool named net-208. The net-208 pool contains addresses from 171.69.233.209/28 to 171.69.233.222/28.

Because the "overload" keyword is missing from the command-line output PAT and NAT can be excluded as being possible correct options. Static NAT is a mapping of an unregistered IPv4 address to a registered IPv4 address on a one-to-one basis that does not involve an address pool as indicated in the output.