CCNA 1 v7 – ITN v7.02 – Modules 8 – 10: Communicating Between Networks Exam | Practice Online Exam

There are three major phases to the bootup process of a Cisco router:

1. Perform the POST and load the bootstrap program.
2. Locate and load the Cisco IOS software.
3. Locate and load the startup configuration file

If a startup configuration file cannot be located, the router will enter setup mode by displaying the setup mode prompt.

Both the console and AUX ports can be used to directly connect to a Cisco network device for management purposes. However, it is more common to use the console port. The AUX port is more often used for remote access via a dial up connection. SSH and Telnet are both remote access methods that depend on an active network connection. SSH uses a stronger password authentication than Telnet uses and also uses encryption on transmitted data.

While at the privileged mode prompt such as Router#, type exit ,press Enter , and the banner message appears. Power cycling a network device that has had the banner motd command issued will also display the banner message, but this is not a quick way to test the configuration.

1. provides security on the console => Router(config-line)# password class: This command sets the console line password to "class", which will be required to access the router console.
2. displays a message when the router is accessed => Router(config)# banner motd #: This command sets a Message of the Day (MOTD) banner, which is a message displayed to all users who log into the router.
3. configures a name on the router => Router(config)# hostname CL1: This command changes the router's hostname to "CL1".

Router(config)# enable password Cisco: This command sets the enable password to "Cisco" for gaining elevated access to the router (privileged EXEC mode).

The Layer 2 device, such as a switch, uses the destination MAC address to determine which path (interface or port) should be used to send the data onward to the destination device.

The ARP cache is used to store IPv4 addresses and the Ethernet physical addresses or MAC addresses to which the IPv4 addresses are mapped. Incorrect mappings of IP addresses to MAC addresses can result in loss of end-to-end connectivity.

PC1 must have a MAC address to use as a destination Layer 2 address. PC1 will send an ARP request as a broadcast and R1 will send back an ARP reply with its G0/0 interface MAC address. PC1 can then forward the packet to the MAC address of the default gateway, R1.

In an ARP spoofing attack, a malicious host intercepts ARP requests and replies to them so that network hosts will map an IP address to the MAC address of the malicious host.

IPv6 does not use ARP. Instead, ICMPv6 neighbor discovery is used by sending neighbor solicitation and neighbor advertisement messages.

The MAC address of PC3 is not present in the MAC table of the switch. Because the switch does not know where to send the frame that is addressed to PC3, it will forward the frame to all the switch ports, except for port 4, which is the incoming port.

Issuing the arp –d * command on a PC will clear the ARP cache content. This is helpful when a network technician wants to ensure the cache is populated with updated information.

The purpose of an ARP request is to find the MAC address of the destination host on an Ethernet LAN. The ARP process sends a Layer 2 broadcast to all devices on the Ethernet LAN. The frame contains the IP address of the destination and the broadcast MAC address, FFFF.FFFF.FFFF. The host with the IP address that matches the IP address in the ARP request will reply with a unicast frame that includes the MAC address of the host. Thus the original sending host will obtain the destination IP and MAC address pair to continue the encapsulation process for data transmission.

One of the negative issues with ARP requests is that they are sent as a broadcast. This means all devices on the local link must receive and process the request.

A switch will flood a frame out of every port, except the one that the frame was received from, under two circumstances. Either the frame has the broadcast address as the destination address, or the destination address is unknown to the switch.

When a PC wants to send data on the network, it always knows the IP address of the destination. However, it also needs to discover the MAC address of the destination. ARP is the protocol that is used to discover the MAC address of a host that belongs to the same network.

The Flow Label in IPv6 header is a 20-bit field that provides a special service for real-time applications. This field can be used to inform routers and switches to maintain the same path for the packet flow so that packets will not be reordered.

Hosts must maintain their own local routing table to ensure that network layer packets are directed to the correct destination network. This local table typically contains a route to the loopback interface, a route to the network that the host is connected to, and a local default route, which represents the route that packets must take to reach all remote network addresses.

Routing table entries for remote routes will have a next hop IP address. The next hop IP address is the address of the router interface of the next device to be used to reach the destination network. Directly-connected and local routes have no next hop, because they do not require going through another router to be reached.

Because the loopback test sends packets back to the host device, it does not provide information about network connectivity to other hosts. The loopback test verifies that the host NIC, drivers, and TCP/IP stack are functioning.

Packets with a destination of 172.17.6.15 are forwarded through Fa0/0. Packets with a destination of 172.17.10.5 are forwarded through Fa1/1. Packets with a destination of 172.17.12.10 are forwarded through Fa1/0. Packets with a destination of 172.17.14.8 are forwarded through Fa0/1. Because network 172.17.8.0 has no entry in the routing table, it will take the gateway of last resort, which means that packets with a destination of 172.17.8.20 are forwarded through Serial0/0/0. Because a gateway of last resort exists, no packets will be dropped.

It is the Protocol field in the IP header that identifies the upper-layer protocol the packet is carrying. The Version field identifies the IP version. The Differential Services field is used for setting packet priority. The Identification field is used to reorder fragmented packets.

The IPv6 simplified header offers several advantages over IPv4:
· Better routing efficiency and efficient packet handling for performance and forwarding-rate scalability
· No requirement for processing checksums
· Simplified and more efficient extension header mechanisms (as opposed to the IPv4 Options field)
· A Flow Label field for per-flow processing with no need to open the transport inner packet to identify the various traffic flows

The value of the Time-to-Live (TTL) field in the IPv4 header is used to limit the lifetime of a packet. The sending host sets the initial TTL value; which is decreased by one each time the packet is processed by a router. If the TTL field decrements to zero, the router discards the packet and sends an Internet Control Message Protocol (ICMP) Time Exceeded message to the source IP address. The Differentiated Services (DS) field is used to determine the priority of each packet. Sequence Number and Acknowledgment Number are two fields in the TCP header.

Internet Protocol (IP) is a network layer protocol that does not require initial exchange of control information to establish an end-to-end connection before packets are forwarded. Thus, IP is connectionless and does not provide reliable end-to-end delivery by itself. IP is media independent. User data segmentation is a service provided at the transport layer.

A default gateway address allows a switch to forward packets that originate on the switch to remote networks. A default gateway address on a switch does not provide Layer 3 routing for PCs that are connected on that switch. A switch can still be accessible from Telnet as long as the source of the Telnet connection is on the local network.

The OSI network layer provides several services to allow communication between devices:addressing
encapsulation
routing
de-encapsulation
Error detection, placing frames on the media, and collision detection are all functions of the data ink layer.

When a packet arrives at the router interface, the router examines its header to determine the destination network. If there is a route for the destination network in the routing table, the router forwards the packet using that information. If there are two or more possible routes to the same destination, the metric is used to decide which route appears on the routing table. The lower the metric, the better the route.

The large number of public IPv6 addresses eliminates the need for NAT. Sites from the largest enterprises to single households can get public IPv6 network addresses. This avoids some of the NAT-induced application problems that are experienced by applications that require end-to-end connectivity.

IP protocol is a connection-less protocol, considered unreliable in terms of end-to-end delivery. It does not provide error control in the cases where receiving packets are out-of-order or in cases of missing packets. It relies on upper layer services, such as TCP, to resolve these issues.

The default gateway is the address of the device a host uses to access the Internet or another network. If the default gateway is missing or incorrect, that host will not be able to communicate outside the local network. Because the host can access other hosts on the local network, the network cable and the other parts of the IP configuration are working.

The command to use for this activity is show ip interface brief in each router. The active and operational interfaces are represented by the value "up" in the "Status" and "Protocol" columns. The interfaces in R1 with these characteristics are G0/0 and S0/0/0. In R2 they are G0/1 and S0/0/0.

Large numbers of ARP broadcast messages could cause momentary data communications delays. Network attackers could manipulate MAC address and IP address mappings in ARP messages with the intent to intercept network traffic. ARP requests and replies cause entries to be made into the ARP table, not the MAC address table. ARP table overflows are very unlikely. Manually configuring static ARP associations is a way to prevent, not facilitate, ARP poisoning and MAC address spoofing. Multiple ARP replies resulting in the switch MAC address table containing entries that match the MAC addresses of connected nodes and are associated with the relevant switch port are required for normal switch frame forwarding operations. It is not an ARP caused network problem.

When a host needs to send a message to another host located on the same network, it can forward the message directly. However, when a host needs to send a message to a remote network, it must use the router, also known as the default gateway. This is because the data link frame address of the remote destination host cannot be used directly. Instead, the IP packet has to be sent to the router (default gateway) and the router will forward the packet toward its destination. Therefore, if the default gateway is incorrectly configured, the host can communicate with other hosts on the same network, but not with hosts on remote networks.

The command copy running-config startup-config copies the running-configuration file from RAM into NVRAM and saves it as the startup-configuration file. Since NVRAM is none-volatile memory it will be able to retain the configuration details when the router is powered off.

A router accepts a packet and accesses its routing table to determine the appropriate exit interface based on the destination address. The router then forwards the packet out of that interface.

The default gateway is used to route packets destined for remote networks. The default gateway IP address is the address of the first Layer 3 device (the router interface) that connects to the same network.

The three commands needed to password protect the console port are as follows:
line console 0
password cisco
login
The interface fastethernet 0/0 command is commonly used to access the configuration mode used to apply specific parameters such as the IP address to the Fa0/0 port. The line vty 0 4 command is used to access the configuration mode for Telnet. The 0 and 4 parameters specify ports 0 through 4, or a maximum of five simultaneous Telnet connections. The enable secret command is used to apply a password used on the router to access the privileged mode.

The enable command is entered at the R1> prompt. The login command is entered at the R1(config-line)# prompt. The copy running-config startup-config command is entered at the R1# prompt. The interface fastethernet 0/0 command is entered at the R1(config)# prompt.

When a host sends packets to a destination outside of its local network, the first hop IP address encountered is the default gateway.

The transport input ssh command when entered on the switch vty (virtual terminal lines) will encrypt all inbound controlled telnet connections.

A default gateway address is typically configured on all devices to allow them to communicate beyond just their local network.In a switch this is achieved using the command ip default-gateway <ip address>.

If a router cannot locate the startup-config file in NVRAM, it will enter setup mode to allow the configuration to be entered from the console device.

The enable command is entered in R1> mode. The login command is entered in R1(config-line)# mode. The copy running-config startup-config command is entered in R1# mode. The ip address 192.168.4.4 255.255.255.0 command is entered in R1(config-if)# mode. The service password-encryption command is entered in global configuration mode.

In the given configuration, the router interface "gi0/0" is connected to the Payroll LAN with the IP address 10.27.14.148. This router interface serves as the gateway for hosts in the Payroll LAN.

So, the IP address that would be configured as the default gateway on the new host in the Payroll LAN is 10.27.14.148. This IP address is the one assigned to the router's interface connected to the Payroll LAN and would be used as the default gateway for hosts in that LAN to communicate with remote networks.

In the given configuration, the router interface "gi0/1" is connected to the Registrar LAN with the IP address 192.168.235.234. This router interface serves as the gateway for hosts in the Registrar LAN.

So, the IP address that would be configured as the default gateway on the new host in the Registrar LAN is 192.168.235.234. This IP address is the one assigned to the router's interface connected to the Registrar LAN, and it would be used as the default gateway for hosts in that LAN to communicate with remote networks.

In the given configuration, the router interface "gi0/1" is connected to the Medical LAN with the IP address 192.168.201.200. This router interface serves as the gateway for hosts in the Medical LAN.

So, the IP address that would be configured as the default gateway on the new host in the Medical LAN is 192.168.201.200. This IP address is the one assigned to the router's interface connected to the Medical LAN and would be used as the default gateway for hosts in that LAN to communicate with remote networks.

In the given configuration, the router interface "gi0/1" is connected to the Service LAN with the IP address 192.168.167.166. This router interface serves as the gateway for hosts in the Service LAN.

So, the IP address that would be configured as the default gateway on the new host in the Service LAN is 192.168.167.166. This IP address is the one assigned to the router's interface connected to the Service LAN and would be used as the default gateway for hosts in that LAN to communicate with remote networks.

In the given configuration, the router interface "gi0/0" is connected to the Store LAN with the IP address 172.20.132.13. This router interface serves as the gateway for hosts in the Store LAN.

So, the IP address that would be configured as the default gateway on the new host in the Store LAN is 172.20.132.13. This IP address is the one assigned to the router's interface connected to the Store LAN and would be used as the default gateway for hosts in that LAN to communicate with remote networks.

In the given configuration, the router interface "gi0/0" is connected to the Store LAN with the IP address 172.19.98.230. This router interface serves as the gateway for hosts in the Store LAN.

So, the IP address that would be configured as the default gateway on the new host in the Store LAN is 172.19.98.230. This IP address is the one assigned to the router's interface connected to the Store LAN and would be used as the default gateway for hosts in that LAN to communicate with remote networks.

In the given configuration, the router interface "gi0/0" is connected to the Manager LAN with the IP address 10.118.62.196. This router interface serves as the gateway for hosts in the Manager LAN.

So, the IP address that would be configured as the default gateway on the new host in the Manager LAN is 10.118.62.196. This IP address is the one assigned to the router's interface connected to the Manager LAN, and it would be used as the default gateway for hosts in that LAN to communicate with remote networks.

In the given configuration, the router interface "gi0/1" is connected to the Registrar LAN with the IP address 192.168.225.223. This router interface serves as the gateway for hosts in the Registrar LAN.

So, the IP address that would be configured as the default gateway on the new host in the Registrar LAN is 192.168.225.223. This IP address is the one assigned to the router's interface connected to the Registrar LAN, and it would be used as the default gateway for hosts in that LAN to communicate with remote networks.

In the given configuration, the router interface "gi0/1" is connected to the Medical LAN with the IP address 192.168.191.189. This router interface serves as the gateway for hosts in the Medical LAN.

So, the IP address that would be configured as the default gateway on the new host in the Medical LAN is 192.168.191.189. This IP address is the one assigned to the router's interface connected to the Medical LAN, and it would be used as the default gateway for hosts in that LAN to communicate with remote networks.

In the given configuration, the router interface "gi0/1" is connected to the Service LAN with the IP address 172.29.157.156. This router interface serves as the gateway for hosts in the Service LAN.

So, the IP address that would be configured as the default gateway on the new host in the Service LAN is 172.29.157.156. This IP address is the one assigned to the router's interface connected to the Service LAN, and it would be used as the default gateway for hosts in that LAN to communicate with remote networks.

The property of ARP (Address Resolution Protocol) that causes the NICs receiving an ARP request to pass the data portion of the Ethernet frame to the ARP process is:

"The type field 0x806 appears in the header of the Ethernet frame."
The Ethernet frame type field, with a value of 0x806, indicates that the frame contains ARP information. When NICs receive an Ethernet frame with this specific type field, they recognize that the frame contains ARP data and forward it to the ARP process to handle the ARP request. This allows the NIC to pass the ARP request to the appropriate software layer for processing and resolution of IP addresses to MAC addresses.

The property of ARP (Address Resolution Protocol) that causes the NICs receiving an ARP request to pass the data portion of the Ethernet frame to the ARP process is:

"The type field 0x806 appears in the header of the Ethernet frame."
The Ethernet frame type field indicates the protocol being used within the data portion of the frame. In the case of ARP, the type field is set to 0x806, which signifies that the frame contains ARP information. When a NIC receives an Ethernet frame with this type field, it recognizes that the frame contains ARP data and forwards it to the ARP process to handle the ARP request. This allows the NIC to pass the ARP request to the appropriate software layer for processing and resolution of IP addresses to MAC addresses.

The property of ARP (Address Resolution Protocol) that causes the ARP request to be flooded out all ports of a switch except for the port receiving the ARP request is:

"The destination MAC address FF-FF-FF-FF-FF-FF appears in the header of the Ethernet frame."
In an ARP request, the destination MAC address is set to the broadcast address FF-FF-FF-FF-FF-FF. When the switch receives a frame with a broadcast MAC address, it floods the frame out to all ports except for the port from which the frame was received. This behavior ensures that all devices on the local network segment have the opportunity to process the ARP request and respond if necessary, as ARP requests are used to resolve IP addresses to MAC addresses and discover the MAC addresses of devices on the local network.

The property of ARP (Address Resolution Protocol) that causes a reply only to be sent to the source sending an ARP request is:

"The source MAC address appears in the header of the Ethernet frame."
When a host sends an ARP request to resolve an IP address to a MAC address, it includes its own MAC address in the source MAC address field of the Ethernet frame. The host that receives the ARP request and has the matching IP address in its ARP table responds with an ARP reply, and it puts its own MAC address in the source MAC address field of the reply frame. This allows the requesting host to associate the IP address with the correct MAC address and update its ARP cache. The ARP reply is unicast and sent directly back to the source that made the ARP request.

The property of ARP (Address Resolution Protocol) that forces all Ethernet NICs to process an ARP request is:

"The destination MAC address FF-FF-FF-FF-FF-FF appears in the header of the Ethernet frame."
When an ARP request is sent, it is broadcast with a destination MAC address of FF-FF-FF-FF-FF-FF, which is a broadcast address. This means that the frame will be received and processed by all NICs on the local network segment, forcing each NIC to check whether the ARP request is relevant to it. NICs compare the target IP address in the ARP request to their own IP address, and the one that matches responds with an ARP reply. This is how ARP works to resolve IP addresses to MAC addresses on a local network.

The property of ARP (Address Resolution Protocol) that allows hosts on a LAN to send traffic to remote networks is:

"Local hosts learn the MAC address of the default gateway."
When a host on a local network wants to communicate with devices on remote networks, it needs to know the MAC address of its default gateway (typically a router). The local hosts learn the MAC address of the default gateway through ARP. They use the ARP protocol to resolve the IP address of the default gateway to its corresponding MAC address. Once they have this MAC address, they can encapsulate their data in Ethernet frames and send it to the default gateway, which is responsible for routing the traffic to remote networks.

Local hosts learn the MAC address of the default gateway.
This is the correct answer. ARP enables a host on a local network to discover the MAC address of the default gateway (usually a router), which is necessary to route traffic to a remote network. When a host sends a packet to a destination outside its local network, it uses ARP to find the MAC address of the default gateway. The packet is then sent to this MAC address, and the gateway routes it towards the remote network.

The destination MAC address FF-FF-FF-FF-FF-FF appears in the header of the Ethernet frame.
This is incorrect in the context of ARP's role in sending traffic to remote networks. The MAC address FF-FF-FF-FF-FF-FF is a broadcast address used in ARP requests within a local network, particularly when a device is trying to discover the MAC address associated with an IP address. This broadcast address is not used for sending traffic to remote networks.

The source MAC address appears in the header of the Ethernet frame.
While this statement is true, it's not specific to ARP's functionality for remote network communication. The source MAC address is part of the Ethernet frame and is used to identify the sending device on the local network. This information is important in all Ethernet communications, not just in the context of ARP or communicating with remote networks.

The port-to-MAC address table on a switch has the same entries as the ARP table on the switch.
This statement is incorrect. The port-to-MAC address table (also known as the MAC address table) on a switch maps MAC addresses to switch ports, helping the switch efficiently forward frames within the local network. On the other hand, the ARP table maps IP addresses to MAC addresses. These tables serve different purposes and contain different types of information. Additionally, switches typically do not maintain ARP tables as this is a function of devices that use IP addressing, like routers and hosts.

The property of ARP (Address Resolution Protocol) that allows MAC addresses of frequently used servers to be fixed in the ARP table is:

"A static IP-to-MAC address entry can be entered manually into an ARP table."
By manually configuring static entries in the ARP table, you can ensure that the MAC addresses of frequently used servers remain fixed in the table and do not get replaced or purged due to the normal dynamic entry aging and timeout. This is a way to maintain stable and predictable mappings for specific devices in the ARP cache.

The property of ARP (Address Resolution Protocol) that allows MAC addresses of frequently used servers to be fixed in the ARP table is:

"A static IP-to-MAC address entry can be entered manually into an ARP table."
By manually configuring static entries in the ARP table, you can ensure that the MAC addresses of frequently used servers remain fixed in the table and do not get purged due to the normal dynamic entry timeout. This is a common practice in network management to maintain stability for specific devices.

Entries in an ARP (Address Resolution Protocol) table are time-stamped, and they are indeed purged after the timeout expires. ARP cache entries are dynamic and have a limited lifetime, typically set to a specific timeout value. When the timeout for a specific entry expires, it is removed from the ARP table to ensure that the table remains up-to-date. Thank you for the clarification.

The term that describes a field in the IPv4 packet header that contains a 4-bit binary value set to 0100 is "version." The "version" field in the IPv4 header is a 4-bit field that indicates the version of the Internet Protocol being used, and in the case of IPv4, it's set to 0100, which represents version 4. This field helps routers and devices understand which IP protocol version is being used in the packet.

The term that describes a field in the IPv4 packet header used to identify the next-level protocol is "protocol." In the IPv4 header, the "Protocol" field is an 8-bit field that specifies the protocol used in the data portion of the packet, indicating which higher-level protocol is being carried within the IP packet. Common values for this field include 6 for TCP (Transmission Control Protocol) and 17 for UDP (User Datagram Protocol), among others.

The term that describes a field in the IPv4 packet header that contains a 4-bit binary value set to 0100 is "version." The "version" field in the IPv4 header is a 4-bit field that indicates the version of the Internet Protocol being used, and in the case of IPv4, it's set to 0100, which represents version 4. This field helps routers and devices understand which IP protocol version is being used in the packet.

The term that describes a field in the IPv4 packet header used to limit the lifetime of a packet is "TTL," which stands for "Time to Live." The TTL field is an 8-bit value in the IPv4 header that represents the maximum number of hops (routers) that a packet can traverse before it is discarded. TTL helps prevent packets from circulating endlessly in the network and is primarily used for network stability and loop prevention. As each router processes the packet, it decrements the TTL value by one, and if the TTL reaches zero, the packet is dropped. This field ensures that packets do not endlessly loop through the network and helps in their efficient delivery.

The term that describes a field in the IPv4 packet header that contains a unicast, multicast, or broadcast address is the "destination IPv4 address." The destination IPv4 address specifies where the packet should be delivered to in the network. It can be set to a unicast address for point-to-point communication, a multicast address for delivery to a group of recipients, or a broadcast address for delivery to all devices on the local network segment. The destination address plays a crucial role in determining how the packet is routed and delivered in the network.

The term that describes a field in the IPv4 packet header that contains a 32-bit binary value associated with an interface on the sending device is "source IPv4 address." The source IPv4 address is a 32-bit value that identifies the source of the IP packet and is typically associated with the interface or network adapter on the sending device through which the packet is transmitted. This address helps routers and other network devices determine the origin of the packet and where replies should be sent.

The term that describes a field in the IPv4 packet header used to detect corruption in the IPv4 header is the "header checksum." The header checksum is a 16-bit field that contains a value computed based on the bits in the header. It is used to verify the integrity of the header during transmission. When the packet is received, the recipient can recalculate the checksum, and if it doesn't match the value in the header, it indicates that the header has been corrupted in transit, and the packet may be discarded. This helps ensure the reliability of the header information.

The term that describes a field in the IPv4 packet header that contains a 32-bit binary value associated with an interface on the sending device is "source IPv4 address." The source IPv4 address is a 32-bit value that identifies the source of the IP packet and is typically associated with the interface or network adapter on the sending device through which the packet is transmitted. This address helps routers and other network devices determine the origin of the packet and where replies should be sent.

The term that describes a field in the IPv4 packet header that contains an 8-bit binary value used to determine the priority of each packet is "Differentiated Services" (often abbreviated as DSCP or DS field). The Differentiated Services field is used for Quality of Service (QoS) and packet prioritization in IP networks. It allows packets to be marked with a value that represents their relative priority, and routers and network devices can use this value to make forwarding and queuing decisions based on the desired quality of service for different types of traffic.

The term that describes a field in the IPv4 packet header used to identify the next-level protocol is "protocol." In the IPv4 header, the "Protocol" field is an 8-bit field that specifies the protocol used in the data portion of the packet, indicating which higher-level protocol is being carried within the IP packet. Common values for this field include 6 for TCP (Transmission Control Protocol) and 17 for UDP (User Datagram Protocol), among others.