Routers Review Questions

Front 1

What are the main functions of a router?

Back 1

Packet switching, Packet filtering, Internetwork communication, Path selection

Front 2

What is the bootstrap?

Back 2

Stored in the microcode of the ROM, the bootstrap is used to bring a router up during initialization. It will boot the router and then load IOS.

Front 3

What is the POST?

Back 3

Stored in the ROM, the POST is used to check the basic functionality of the hardware and determines which interfaces are present.

Front 4

What is ROM Monitor?

Back 4

Stored in the ROM, the ROM monitor is used for manufacturing, testing, and troubleshooting.

Front 5

What is Mini-IOS?

Back 5

Called the RXBOOT or bootloader by Cisco, is stored in ROM and can be used to bring up an interface and load IOS into flash; also other maintenance features

Front 6

What is stored in RAM when running IOS?

Back 6

Packet buffers, ARP cache, routing tables, running-config, IOS after boot.

Front 7

What is the ROM?

Back 7

It stands for Read-only memory, it is used to start and maintain the router, holds POST, bootstrap and mini-IOS.

Front 8

What is Flash Memory for?

Back 8

It stores IOS by default.

Front 9

What is the Configuration Register?

Back 9

Used to control how the router boots up. This value can be found as the last line of the show version command output and by default is set to 0x2102

Front 10

What is boot order for a Cisco router?

Back 10

POST -> Bootstrap loads IOS -> IOS looks for startup-config in NVRAM and places into RAM (Looks for TFTP server if not in NVRAM)

Front 11

What is CDP?

Back 11

Cisco Discovery Protocol is used for learning about other devices that are connected to the Cisco device you are using.

Front 12

What does "show CDP" command do?

Back 12

It will show which interfaces the devices are plugged into, the models of the devices, the device IDs and the CDP packet hold time (only for Cisco devices).

Front 13

What is a host table?

Back 13

It is the local DNS on a router

Front 14

What are the three types of interface found on a Cisco router

Back 14

LAN (FastEthernet), WAN (Serial), The Management Ports (Auxiliary and Console ports)

Front 15

Where is the startup-configuration stored?

Back 15

In NVRAM (Non-volatile Random Access Memory)

Front 16

What is split-horizon (RIP)?

Back 16

It prohibits a router from advertising a route back onto the interface from which it was learned (RIP)

Front 17

What is the hold down timer and the flush timer (RIP)?

Back 17

A router will start a timer when they hear a network is unreachable. Until the timer expires, the router will discard any subsequent route messages that indicate the route is in fact reachable.

The flush timer starts at the same time and is longer than the hold down timer. Once it expires, the invalid route will be flushed from the routing table.

Front 18

What is the invalid timer in RIP?

Back 18

How many seconds, since seeing a valid update, to consider the route invalid, and placing the route into hold down

Front 19

What is the LSRefreshtime?

Back 19

In OSPF, even if there is not change in routes, it will flood its own LSA Packets every 30 minutes.

Front 20

What is OSPF's algorithm?

Back 20

Dijkstra’s SPF

Front 21

How do routers using Link State Routing Protocols reach convergence?

Back 21

Each routers learns its own directly connected networks

Link state routers exchange hello packet to “meet” other directly Connected link state routers

Each router builds its own Link State Packet (LSP) which includes information about neighbors such as neighbor ID, link type, & bandwidth

the router floods the LSP to all its neighbors who then store the information and then forward it until all routers have the same information

Once all the routers have received all the LSPs, the routers then construct a topological map of the network which is used to determine the best routes to a destination

Front 22

What is convergence?

Back 22

Convergence is the state of a set of routers that have the same topological information about the internetwork in which they operate

Front 23

What is a Router ID?

Back 23

Used to identify the routers in the OSPF network

Can be set manually to an IP address or it is automatically selected by:

Highest loopback address or the highest active IP address

Front 24

What is the default OSPF cost on CISCO routers?

Back 24

10^8/bandwidth but it can be changed

Front 25

What are the Steps of OSPF Operation?

Back 25

Steps of OSPF Operation:
Establish Router Adjacencies
Elect a designated router and a backup designated router
Discover routes
Select appropriate route to use
Maintain routing information

Front 26

The Designated Router is elected by ___________.

Back 26

the highest Router ID

Front 27

In OSPF the __________ and ___________ intervals must be the same.

Back 27

hello and dead

Front 28

The "default-information originate" command is used to:

Back 28

It tells OSPF to advertise a default route if there is one.

Front 29

When looking at the show ip route command, what does [110/782] mean?

Back 29

It signifies Administrative Distance/metric

Front 30

What is a Link State?

Back 30

Routing Protocols are able to take into account more complicated metrics of a link, such as bandwidth, reliability, and load.

Front 31

In reference to Routing Protocols, what does convergence mean?

Back 31

When routers know the full topology of the entire network and are then capable of participating in routing.

Front 32

When OSPF is in use, the three criteria used to decide which router will be the Designated Router are:

Back 32

The Router_ID, the highest Loopback IP Address , the highest IP Address of any active interface

Front 33

What is the purpose of a Default Route?

Back 33

If no matches are found in the routing table, it is sent to through the default route. This is usually set on the edge router's interface to the internet.

Front 34

Describe the following NAT terms:
Inside Local Address
Outside Local Address
Inside Global Address
Outside Global Address

Back 34

Inside (Where the node is), Local (perspective)

Inside Local Address: The source address as it is seen within the LAN, before NATing occurs.

Outside Local Address: The destination address as seen inside the destination node's network (After NAT changes the public IP to the private IP)

Inside Global Address: The source address as it is seen from outside the LAN (the address of the node after NAT occured)

Outside Global Address: The destination address from outside the destination node's network (Before NATing takes place at the destination network)

Front 35

What is SNMP?

Back 35

Simple Network Management Protocol (SNMP) is an "Internet-standard protocol for managing devices on IP networks"

Front 36

Where is VLAN information stored?

Back 36

VLAN information is stored in flash (vlan.dat)

Front 37

What are the options for Port Security (Switch)?

Back 37

Protect, Restrict, Shutdown

Front 38

Three distinct functions of layer 2 switching:

Back 38

o Address learning
o Forward/filter decisions
o Loop avoidance

Front 39

What is a Native VLAN?

Back 39

If a switch receives untagged frames on a trunkport, they are assumed to be part of the VLAN that are designated on the switchport as the Native VLAN.

Front 40

What is the Default VLAN?

Back 40

VLAN 1 on Cisco switches.
Carries CDP and STP (spanning tree protocol) traffic
Do not use it for data, voice or management traffic for security reasons.

Front 41

What is a Dynamic VLAN?

Back 41

Assign a device to a VLAN based on its MAC address.

Front 42

What are Trunk Links?

Back 42

When a trunk port is configured, it begins marking frames as they exit the port to indicate which VLAN each frame is associated with. The trunk port can also read the markings, called tags, as they enter the trunk port. This enables the switch to send a frame only to the ports for the given VLAN associated with the incoming frame.