Chapter 1: Routing Concepts
NVRAM
A network administrator enters the command copy running-config startup-config. Which type of memory will the startup configuration be placed into? flash RAM NVRAM ROM
R1 (config)# banner motd $ Authorized Access Only! $ R1 (config)# end
Basic Router Setting Commands Banner Message
loopback interface
Is a logical interface internal to the router. (not assigned to a physical port, and can never be connected to any other device.) software interface automatically placed in "up" state. *at least one interface will always be available
192.168.12.16
Refer to the image. PC A sends a request to Sever B. What IPv4 address is used in the destination field in the packet as the packet leaves PC A? 192.168.10.10 192.168.11.1 192.168.10.1 192.168.12.16
Gateway of Last Resort
The IP address of the router in your network where data packets with unknown routes should be forwarded
Flash Memory
permanent storage for IOS and other system-related files
(NVRAM) Non-Volatile Random Access Memory
permanent storage for startup configuration file (startup-config)
clock rate command
required on the DCE end when interconnecting two serial interfaces..
R1# show history
shows last 10 commands used
Reliability
the dependability of the components that make up the network, such as the routers, switches, PCs and servers. (probability of failure or as the mean time between failures (MTBF)).
routing table
A data table stored in a router that lists the routes to particular network destinations when packets arrive on router interface, the router uses this to determine how to reach the destination network.
The interface fa0/0 has not been activated
A network administrator configures the interface fa0/0 on the router R1 with the command ip address 172.16.1.254 255.255.255.0. However, when the administrator issues the command show ip route, the routing table does not show the directly connected network. What is the possible cause of the problem? The interface fa0/0 has not been activated. The configuration needs to be saved first. No packets with a destination network of 172.16.1.0 have been sent to R1. The subnet mask is incorrect for the IPv4 address.
switched virtual interface (SVI)
A routed interface on a switch. Another term for any VLAN interface in a Cisco switch. See also VLAN interface.
Process Switching
An older packet forwarding mechanism still available for Cisco routers. packet arrives on an interface, forwarded to control plane where the CPU matches the destination address with an entry in its routing table, and then it determines the exit interface and forwards the packet. *does this for every packet.
Router# configure terminal Router (config)# hostname R1 R1 (config)# enable secret class R1 (config)# line console 0 R1 (config-line)# password cisco R1 (config-line)# login R1 (config-line)# exit R1 (config)# line vty 0 4 R1 (config-line)# password cisco R1 (config-line)# login R1 (config-line)# exit R1 (config)# service password-encryption
Basic Router Settings Commands host name & secure router
CPU Operating System Memory and Storage (RAM, ROM, NVRAM, Flash, Hard Drive)
Components of a router are:
R1 (config)# interface loopback 0 R1 (config-if)# ip address 10.0.0.1 255.255.255.0 R1 (config-if)# end R1 (config)#
Configure loopback inerface
It is the interface on R1 used to send data that is destined for 10.1.1.0/24.
Consider the following routing table entry for R1: D 10.1.1.0/24 [90/2170112] via 209.165.200.226, 00:00:05, Serial0/0/0 What is the significance of the Serial0/0/0? It is the interface on R1 used to send data that is destined for 10.1.1.0/24. It is the R1 interface through which the EIGRP update was learned. It is the interface on the final destination router that is directly connected to the 10.1.1.0/24 network. It is the interface on the next-hop router when the destination IP address is on the 10.1.1.0/24 network.
showing running-config interface interface-id
Displays the commands configured on the specified interface
show ip route show ipv6 route
Displays the contents of the IPv4/IPv6 routing table stored in RAM.
IP address Subnet mask Default gateway
In order for packets to be sent to a remote destination, what three pieces of information must be configured on a host? (Choose three.) hostname IP address subnet mask default gateway DNS server address DHCP server address
no shutdown
Refer to the exhibit. A network administrator has configured R1 as shown. When the administrator checks the status of the serial interface, the interface is shown as being administratively down. What additional command must be entered on the serial interface of R1 to bring the interface up? IPv6 enable clockrate 128000 end no shutdown
R1 does not know a route to any remote networks. The interface Fa0/1 is configured with IPv6 address 2001:DB8:ACAD:A::12.
Refer to the exhibit. A network administrator issues the show ipv6 route command on R1. What two conclusions can be drawn from the routing table? (Choose two.) R1 does not know a route to any remote networks. The network FF00::/8 is installed through a static route command. The interface Fa0/1 is configured with IPv6 address 2001:DB8:ACAD:A::12. Packets that are destined for the network 2001:DB8:ACAD:2::/64 will be forwarded through Fa0/1. Packets that are destined for the network 2001:DB8:ACAD:2::54/128 will be forwarded through Fa0/0.
remove the Ethernet header and configure a new Layer 2 header before sending it out S0/0/0
Refer to the exhibit. If PC1 is sending a packet to PC2 and routing has been configured between the two routers, what will R1 do with the Ethernet frame header attached by PC1? nothing, because the router has a route to the destination network remove the Ethernet header and configure a new Layer 2 header before sending it out S0/0/0 open the header and replace the destination MAC address with a new one open the header and use it to determine whether the data is to be sent out S0/0/0
Send the packet out the Serial0/0/0 interface
Refer to the exhibit. What will the router do with a packet that has a destination IP address of 192.168.12.227? Drop the packet. Send the packet out the Serial0/0/0 interface. Send the packet out the GigabitEthernet0/0 interface. Send the packet out the GigabitEthernet0/1 interface.
R1 (config)# interface G0/0 R1 (config-if)# description Link to LAN1 R1 (config-if)# ip address 192.168.10.1 255.255.255.0 R1 (config-if)# no shutdown R1 (config-if)# exit
Router Interface Configuration Command
Volatile loses it's content when the power is turned off Nonvolatile does not lose it's content when the power is turned off
Router Memory
R1# copy running-config startup-config
Save running configuration command
volatile memory
Storage (such as RAM) that is wiped clean when power is cut off from a device. running IOS running configuration file IP routing and ARP table Packet buffer
nonvolatile memory
Storage that retains data even when powered down (such as flash memory, hard disk storage). ROM - permanent storage for (bootup instructions, basic diagnostic software, basic diagnostic software, limited IOS in case the router cannot load the full-featured IOS. NVRAM - permanent storage for startup configuration file (startup-config) Flash - permanent storage for IOS and other system-related files
Physical Topology
The actual layout of network devices, wires, and cables.
logical topology
The path over which the data is transferred in a network. It describes how the network devices appear connected to network users.
A router connects multiple IP networks It determines the best path to send packets
What are two functions of a router? (Choose two.) A router connects multiple IP networks. It controls the flow of data via the use of Layer 2 addresses. It determines the best path to send packets. It provides segmentation at Layer 2. It builds a routing table based on ARP requests.
If the destination MAC address that corresponds to the IPv4 address is not the ARP cache, R1 sends an ARP request.
What does R1 use as the MAC address of the destination when constructing the frame that will go from R1 to Server B? If the destination MAC address that corresponds to the IPv4 address is not in the ARP cache, R1 sends an ARP request. The packet is encapsulated into a PPP frame, and R1 adds the PPP destination address to the frame. R1 uses the destination MAC address of S1. R1 leaves the field blank and forwards the data to the PC.
It is a logical interface internal to the router
What is a characteristic of an IPv4 loopback interface on a Cisco IOS router? The no shutdown command is required to place this interface in an UP state. It is a logical interface internal to the router. Only one loopback interface can be enabled on a router. It is assigned to a physical port and can be connected to other devices.
A directly connected network
What route would have the lowest administrative distance? a directly connected network a static route a route received through the EIGRP routing protocol a route received through the OSPF routing protocol
IP addresses Layer 1 statuses
What two pieces of information are displayed in the output of the show ip interface brief command? (Choose two.) IP addresses MAC addresses Layer 1 statuses next-hop addresses interface descriptions speed and duplex setting
Destination IP address
When a router receives a packet, what information must be examined in order for the packet to be forwarded to a remote destination? destination MAC address source IP address destination IP address source MAC address
Cisco Express Forwarding
Which packet-forwarding method does a router use to make switching decisions when it is using a forwarding information base and an adjacency table? fast switching Cisco Express Forwarding process switching flow process
Terminal emulation client software
Which software is used for a network administrator to make the initial router configuration securely? SSH client software Telnet client software HTTPS client software terminal emulation client software
Destination IP address Subnet mask
Which two items are used by a host device when performing an ANDing operation to determine if a destination address is on the same local network? (Choose two.) destination IP address destination MAC address source MAC address subnet mask network number
bandwidth delay
Which two parameters are used by EIGRP as metrics to select the best path to reach a network? (Choose two.) hop count bandwidth jitter resiliency delay confidentiality
Administrative distance refers to the trustworthiness of a particular route. Routes with the smallest metric to a destination indicate the best path.
Which two statements correctly describe the concepts of administrative distance and metric? (Choose two.) Administrative distance refers to the trustworthiness of a particular route. A router first installs routes with higher administrative distances. The value of the administrative distance cannot be altered by the network administrator. Routes with the smallest metric to a destination indicate the best path. The metric is always determined based on hop count. The metric varies depending on which Layer 3 protocol is being routed.
Cisco Express Forwarding (CEF)
builds a Forwarding Information Base (FIB), and an adjacency table. Entries are not packet-triggered like fast switching but change-triggered (when something changes in network topology).
R1 (config)# no ip domain-lookup
disable DNS lookup command
show ip interface brief show ipv6 interface brief
displays a summary for all interfaces, including the IPv4/IPv6 address of the interface and current operation
ipv6 unicast-routing command
enables IPv6 routing enables a PC connected to the interface to automatically configure an IPv6 address to set a default gateway w/o needing the services of a DHCPv6 server. routers begins sending ICMPv6 Router Advertisement messages out the interface.
Scalability
how easily the network can accommodate more users and data transmission requirements.
Security
how protected the network is (including the information that is transmitted over the network).
R1# terminal history size
increase or decrease the size of the buffer
Cost
indicates the general expense for purchasing of network components, and installation and maintenance of the network.
Point-to-Point Protocol (PPP)
is a data link layer (layer 2) communications protocol between two routers directly without any host or any other networking in between.
local host route
is for routes owning the IP address, allows router to process packets to that IP. has an administrative distance of 0. has a mask of /32 (IPv4) /128 (IPv6).
speed
is measure of the data rate in bits per second b/s of a given link in the network.
(ROM) Read-Only Memory (nonvolatile)
permanent storage for (bootup instructions, basic diagnostic software, basic diagnostic software, limited IOS in case the router cannot load the full-featured IOS.
clock rate
serial interface connecting to the serial cable end labeled DEC must e configured with the ________________________ command.
Routing Protocol
specifies how routers communicate with each other to distribute information that enables them to select routes between any two nodes on a computer network.
Availability
the likelihood that the network is available for use when it is required.
Fast-Switching
uses fast switching cache to store next-hop information. packet arrives on an interface, forwarded to control plane where the CPU searches for a match in the fast-switching cache. If it is not there, it is process-switched and forwarded to the exit interface.
