11-1-2011/ccent/ccna Icnd1:chapter 5

Front 1

Which of the following are functions of OSI layer 3 protocols?
a. Logical addressing
b. Physical addressing
c. Path selection
d. Arbitration
e. Error recovery

Back 1

a,c
The network layer defines logical addressing, in contrast to physical addressing. The logical address sctructure allows for easy grouping of addresses, which makes routing more efficient. Path selection refers to the process of choosing the best routes to use in the network. Physical addressing and arbitration typically are data link layer functions, and error recovery typically is a transport layer function.

Front 2

Imagine that PC1 needs to send some data to PC2 and PC1 and PC2 are separated by several routers. What are the largest entities that make it from PC1 to PC2?
a. Frame
b. Segment
c. Packet
d. L5 PDU
e. L3 PDU
f . L1 PDU

Back 2

c,e
Packet
L3 PDU

Front 3

Imagine a network with two routers that are connected with a point to point DLC serial link. Each router has an Ethernet, with PC1 sharing the Ethernet with Router 1 and PC2 sharing the Ethernet with Router2. When PC1sends data to PC2 which of the following is true?
a. Router 1 strips the Ethernet header and trailer off the frame received from PC1 never to be used again.
b. Router 1 encapsulates the Ethernet frame inside an HDLC header and sends the frame to Router2 which extracts the Ethernet frame for forwarding to PC2.
c. Router 1 strips the Ethernet header and trailer off the frame received from PC1 which is exactly re-created by R2 before forwarding data to PC2.
d. Router 1 removes the Ethernet, IP, and TCP headers and rebuilds the appropriate headers before forwarding the packet to Router2

Back 3

a
Router 1 strips the Ethernet header and trailer off the frame received from PC1 never to be used again

Front 4

Which of the following are valid Class C IP addresses that can be assigned to hosts.
a. 1.1.1.1
b. 200.1.1.1
c. 128.128.128.128
d. 224.1.1.1
e. 223.223.223.255

Back 4

b
200.1.1.1 is a class D address. 223.223.223.255 is the network broadcast address for class C network 223.223.223.0, so it cannot be assigned to a host.

Front 5

What is the range of values for the first octet for Class A IP networks?
a. 0 to 127
b. 0 to 126
c. 1 to 127
d. 1 to 126
e. 128 to 191
f. 128 to 192

Back 5

d.
1 to 126

Front 6

PC1 and PC2 are on two different Ethernnets that are separated by an IP router. PC1's IP address is 10.1.1.1, and no subnetting is used. Which of the following addresses could be used for PC2?
a. 10.1.1.2
b. 10.2.2.2
c. 10.200.200.1
d. 9.1.1.1
e. 255.1.1.1
f. 1.1.1.1

Back 6

D and F. Without any subnetting in use, all addresses in the same network as 10.1.1.1 all addresses in class A network 10.0.0.0 must be on the same LAN. Addresses separated from that network by some router cannot be in network 10.0.0.0. So, the two correct answers are the only two answers that list a valid unicast IP address that is not in network 10.0.0.0.

Front 7

Each class B network contians hwo many IP addresses that can be assigned to host
a. 16,777,214
b. 16,777,216
c. 65,536
d. 65,534
e. 65,532
f. 32, 768
g. 32, 766

Back 7

d. 65,534

Front 8

Each class C network contains how many IP addresses that can be assigned to hosts?

a. 65,534
b. 65,532
c. 32,768
d. 32,766
e. 256
f. 254

Back 8

f. 254

Front 9

which of the following does a router normally use when making a decision about routing TCP/IP packets?
a. Destination MAC address
b. Source MAC address
c. Destination IP address
d. Source IP address
e. Destination MAC and IP address

Back 9

c. Destination IP address

Front 10

Which of the following are true about a LAN-connected TCP/IP host and its IP routing (forwarding) choices?
a. The host always sends packets to its default gateway.
b. The host sends packets to its default gateway if the destination IP address is in a different class of IP network than the host.
c. The host sends packets to its default gateway if the destination IP address is in a different subnet than the host.
d. The host sends packets to its default gateway if the destination IP address is in the same subnet as the host.

Back 10

b. The host sends packets to its default gateway if the destination IP address is in a different class of IP network than the host.
c. The host sends packets to its default gateway if the destination IP address is in a different subnet than the host.

Front 11

Which of the wollwing are functions of a routing protocol?
a. Advertising known routes to neighboring routers
b. Learning routes for subnets directly connected to the router.
c. Learning routes, and putting those routes into the routing table, for routes advertised to the router by its neighboring routers
d. To forward IP apckets based on a packet's destination IP address.

Back 11

a. Advertising known routes to neighboring routers
c. Learning routes, and putting those routes into the routing table, for routes advertised to the router by its neighboring routers

Front 12

Which of the following protocols allows a client PC to discover the IP address of another computer based on that other computer's name?
a. ARP
b. RARP
c. DNS
d. DHCP

Back 12

c. DNS

Front 13

Which of the following protocols allows a client PC to request assignment of an IP address as well as learn its default gateway?
a. ARP
b. RARP
c. DNS
d. DHCP

Back 13

d. DHCP

Front 14

What does the OSI network layer protocol define?

Back 14

Routing- the process of forwarding packets (layer 3 PDUs).
Logical addressing- addresses that can be used regardless of the type of physical networks used, providing each device one address. Logical addressing enables the routing process to identify a packets source and destination.
Routing protocol - a protocl that aids routers by dynamically learning about the groups of addresses in the network, which in turns allows the routing (forwarding) process to work well.
Other utilities - The network layer also relies on other utilities. For TCP/IP, these utilities include DNS, DHCP, ARP and ping.

Front 15

What is layer 3 protocol called?

Back 15

Connectionless network services. Only protocols used to day are TCP/IP network protocol.

Legacy ones are IPX, Apple talk, and DDP.

Front 16

Main job of IP?

Back 16

To route data packets from the source host to the destination host

Front 17

What does IP require?

Back 17

Does not require any overhead agreements or messages before sending a packet. Connectionless protocol

Front 18

How does IP deliver the packet?

Back 18

IP tries to deliver each packet, but if a host IP process cannot deliver the packet it is discarded.

Front 19

Does IP use high overhead to deliver its packets?

Back 19

No, It only uses the minimum and prepares each packet with minimum work. (no error check, no resending lost data)

Front 20

What is Routing forwarding?

Back 20

It focus on the end to end logic of forwarding a packet. R1, sends to R2, then R3. Using different interfaces like FA 0/1 or S0/1 to get to the destination.

Front 21

How does a router determine which data-link address to use?

Back 21

It uses the IP address resolution protocol (ARP). It dynamically learns the data a link address of an IP host connected to a LAN

Front 22

Process of routing forwards Layer 3 packets?

Back 22

Called Layer 3 protocol data units L3 PDU, based on the destination of layer 3 address in the packet.

Front 23

What are the routing process used the data link layer to encapsulate the Layer 3 packets?

Back 23

Layer 3 packets into layer2 frames for transmission across each successive data link.

Front 24

Header fields
Version

Back 24

Version of the IP protocol. Most networks use version 4 today

Front 25

IHL

Back 25

IP Header Length. Defines the length of the IP header, including optional fields.

Front 26

DS Field

Back 26

Differentiated services Field. It is used for marking packets for the purpose of applying different quality of service levels to different packets

Front 27

Packet length

Back 27

Identifies the entire length of the IP packet, including the data.

Front 28

Identification

Back 28

Used by the IP packet fragmentation process; all fragments of the original packet contain the same identifier

Front 29

Flags

Back 29

3 bits used by the IP packet fragmentation process

Front 30

Fragment offset

Back 30

A number used to help hosts reassemble fragmented packets into the original larger packet

Front 31

TTL

Back 31

Time to live. A value used to prevent routing loops

Front 32

Protocol

Back 32

A field that identifies the contents of the data portion of the IP packet. For example, protocol 6 implies that TCP header is the first thing in the IP packet data field

Front 33

Header Check sum

Back 33

A value used to store an FCS value, whose purpose is to determine if any bit errors occurred in the IP header.

Front 34

Source IP address

Back 34

The 32-bit IP address of the sender of the packet.

Front 35

Destination IP address

Back 35

The 32-bit IP address of the intended recipient of the packet.

Front 36

What does a IPv4 header look like?

Back 36

Contains:
Version
IP header Length
Differentiated Services Field
Packet length
Identification
Flags
Fragment offset
Time to Live
Protocol
Header Check sum
Source IP address
Destination IP Address

Front 37

What does a IPv4 header look like?

Back 37

Contains:
Version
IP header Length
Differentiated Services Field
Packet length
Identification
Flags
Fragment offset
Time to Live
Protocol
Header Check sum
Source IP address
Destination IP Address

Front 38

What does a IPv4 header look like?

Back 38

Contains:
Version
IP header Length
Differentiated Services Field
Packet length
Identification
Flags
Fragment offset
Time to Live
Protocol
Header Check sum
Source IP address
Destination IP Address

Front 39

A key feature of network layer addresses is that ?

Back 39

They were designed to allow logical grouping of addresses. Numeric value of an address implies a group or set of addresses, which are in the same group

Front 40

What does routing rely on?

Back 40

The fact that layer 3 addresses are grouped. The routing tables for each network layer protocol can have one entry for the group, not one entry for each individual address.

Front 41

A Ethernet with 100 TCP/IP host will need to forward how many entries?

Back 41

Only one routing table entry representing the entire group of hosts on the Ethernet. to make networking more efficient network layer protocols group addresses.

Front 42

How does a router make correct choices to send packets?

Back 42

Each router needs a routing table, with a route that matches the packet sent to PC2. The routes tell the router where to send the packet next

Front 43

How do routers build their routing tables?

Back 43

Routers build their routing tables dynamically using routing protocol.

Front 44

What do routing protocols do?

Back 44

Routing protocols learn about all the locations of the network layer"groups" in a network and advertise the groups' locations.

Front 45

What is the main goal of a routing protocol?

Back 45

Is to fill the routing table with all known destination groups and with the best route to reach each group.

Front 46

Routing protocol?

Back 46

Learns routes and puts those routes in a routing table.

Front 47

A routed protocol?

Back 47

Defines the type of packet forwarded, or routed, through a network. IP is a routed protocol. If routers use RIP then it would be called a routing protocol.

Front 48

How does a device communicate using TCP/IP?

Back 48

It uses an IP address.

Front 49

Why is an IP address needed?

Back 49

When an device has the software and hardware, It can send and receive IP packets. Any device that can send and receive IP packets is called an IP host.

Front 50

An IP address consists of how many bits?

Back 50

32 bit number written in dotted decimal notation. Each byte is 8 bits of the 32 bit IP address.

Front 51

What is dotted decimal ?

Back 51

It is a 168.1.1.1 is an IP address written in dotted decimal form.

Front 52

What is an octet?

Back 52

Each decimal number in an IP address is called an octet. An octet is just a name for byte 168.1.1.1 the 168 is one octet 1 is another and so on

Front 53

What is the range of decimal numbers in an octet?

Back 53

The range of the decimal numbers in an octet is between 0-255

Front 54

Does every NIC have an different IP address?

Back 54

Yes, each NIC will have a different IP address and different interface.

Front 55

What are tow key points about how IP addresses are organized?

Back 55

All IP addresses in the same group must not be separated by a router.
IP addresses separated by a router must be in different groups.

Front 56

What is the difference between network 8.0.0.0 and 130.4.0.0?

Back 56

They are different because they belong to different classes.

Front 57

How many different network classes are there?

Back 57

Class A
Class B
Class C
Class D multicast
Class E experimental

Front 58

How many number of addresses for a Class A network?

Back 58

2^24 minus 2 or 16,777,216 addresses per network

Front 59

How many number of addresses for a Class B network?

Back 59

2^16 minus 2 or 65,536 address per network

Front 60

How many number of addresses for a Class C network?

Back 60

2^8 minus 2 or 256 address per network

Front 61

What do you call it when an address has all zeros in its host part?

Back 61

If it is all zeros it is called network broad cast or directed broadcast address. All packets sent to a network broadcast are forwarded to all devices in the network.

Front 62

What does each device connected to the internet need?

Back 62

A unique, non-duplicated IP address

Front 63

Who uses class A, B, and C networks?

Back 63

Class A is for schools, ISPs, governments with large scaled networks. Class B is for medium networks and Class C for small typically home networks.

Front 64

What does the central authority do?

Back 64

It assigns each network number to only one organization, helping unique address assignment.

Front 65

What does each organization do when their addressed is assigned to them?

Back 65

The organization then assigns individual IP addresses inside its own network.

Front 66

What is the range of a Class A network?

Back 66

first octet is between 1-126
1.0.0.0 to 126.0.0.0

Front 67

What is the range of a Class B network?

Back 67

first octet is between 128-191
128.0.0.0 to 191.0.0.0

Front 68

What is the range of a Class C network?

Back 68

first octet is between 192-223
192.0.0.0 to 223.255.255.0

Front 69

How many host for a Class A?

Back 69

2^24 -2 or 16,777,214

Front 70

How many host for a Class B?

Back 70

2^16 -2 or 65,534

Front 71

How many hosts are for a Class C network?

Back 71

2^8 -2 or 254

Front 72

What is classful addressing?

Back 72

The three parts of an IP address (network, subnet, and host). It refers to routing based on the rules about class A, B, and C addressing.

Front 73

What is Classless routing?

Back 73

Instead of three parts there are two parts. The part on which routing is based. The host part.

The subnet or prefix part and the host part.

referred as a subnet mask.

Front 74

Using simple routing logic how does a host send a packet?

Back 74

If the destination IP address is in the same subnet as I am, send the packet directly to that host.

If the destination IP address is not in the same subnet send it to the default gateway.

Front 75

What is a routing table?

Back 75

Contains a list of network layer address groupings. There is one single entry in the routing table per individual destination. One routing table per group

Front 76

What does the data link layer do?

Back 76

It asks the physical interface to send the packet. It also adds the header and trailer to the packet making a frame.

Front 77

When are the data-link headers and trailers discarded?

Back 77

When the routing process forwards the packet, end to end through the network discarding the packet headers and trailers along the way.