Ch 6

Question 1

IPv6 traffic class field

Answer 1

1 bytes
replaces DS field

Question 2

version field

Answer 2

4 bit value
IPv4 (0100) vs IPv6 (0110)

Question 3

next hop address

Answer 3

IP of the next router to forward the packet for that network

Question 4

2 Windows commands to show routing table

Answer 4

route print
netstat -r

Question 5

packet sizes

Answer 5

IPv4 - 20 bytes

IPv6 - 40 bytes

Question 6

IPv6 payload length field

Answer 6

16 bits (2 bytes)
length of data payload of packet

Question 7

3 Cisco router types

Answer 7

Branch (ISR G2)
WAN (Catalyst switches, Aggregation Services Routers)
Service Provider (Carrier Routing System and 7600 routers)

Question 8

in-band vs out-of-band

Answer 8

in-band carry user traffic and require IP addressing
out-of-band dedicated to configure, manage, and troubleshoot, don’t carry user traffic

Question 9

definition of routing

Answer 9

the process of sending packets to hosts on a remote network

Question 10

IPv6 hop limit field

Answer 10

8 bit (2 bytes)
replaces TTL field

Question 11

next header

Answer 11

8 bits (2 bytes)
same as IPv4 protocol field
indicates data payload type

Question 12

HWIC

Answer 12

high speed WAN interface card

Question 13

Basic characteristics of a IP

Answer 13

Connectionless
Best effort delivery
Media independent

Question 14

ICMP

Answer 14

Internet Control Message Protocol

Question 15

IPv6 extension headers EH

Answer 15

provide optional network layer information
placed between IPv6 header and payload
used for fragmentation, security, mobility

Question 16

definition of hop

Answer 16

each router that a packet crosses to reach its destination

Question 17

IOS command for viewing routing table

Answer 17

show ip route

Question 18

fragmentation definition

Answer 18

when an intermediate device splits up a packet to forward it over a medium with a smaller MTU
routers don’t fragment IPv6 packets

Question 19

default route definition

Answer 19

a route that device uses to send a packet to a remote network when network doesn’t match any other routes.

Question 20

TTL Time to Live

Answer 20

1 byte
limits the lifetime of packet
each hop TTL is decremented
if 0, router sends ICMP Time Exceeded message

Question 21

improvements of IPv6

Answer 21

longer addresses (128 bits - 16 bytes) vs (32 bits - 4 bytes)
headers have fewer fields
NAT not needed

Question 22

MTU maximum transmission unit

Answer 22

the maximum size of the PDU that a given medium can support
data link layer tells network layer its MTU

Question 23

best effort definition

Answer 23

packet delivery is not guaranteed
cannot retransmit undelivered or corrupt packets

Question 24

function of network layer

Answer 24

enable the transport of data from one network to another.

Question 25

boot process

Answer 25

1. perform post and load bootstrap (ROM)
2. load IOS either from flash or TFTP server. If failure, use limited IOS from ROM (hash symbols)
3. load startup-config from NVRAM

Question 26

gateway of last resort

Answer 26

default route
route that router will use if packet does not match entry in routing table

Question 27

Differentiated Services (DiffServ)

Answer 27

1 byte
used for priority
formerly called Type of Service
DSCP Differentiated Services Code Point (6 bits)
ECN Explicit Congestion Notification (2 bits)

Question 28

Four basic processes of network layer

Answer 28

Addressing end devices
Encapsulation (adding network layer headers)
Routing
De-encapsulation

Question 29

IPv6 flow label field

Answer 29

20 bits (2.5 bytes)
how router should handle packet

packets with the same flow field value should be handled the same

Question 30

Cisco routing table abbreviations

Answer 30

C = directly connected network
L = local interface (IP on interface on router)
S= static router
D = EIGRP enchanced interior gateway routing protocol
O = OSPF Open Shortest Path First

Question 31

3 fields used for fragmentation

Answer 31

Identification
Flags
Fragment offset

Question 32

advanced integration module

Answer 32

offloads processor-intensive functions away from main CPU

Question 33

IPv6 simplified header benefits

Answer 33

better routing efficiency
no requirement for processing checksums
more efficient extension header mechanisms
flow label field

Question 34

connectionless definition

Answer 34

no connection with the destination is established before sending packets
the recipient is not notified in advance
the benefit is there is less overhead for IP

do not know if:

1. receiver present
2. packet arrived
3. receiver can read the packet

Question 35

Cisco types of memory

Answer 35

RAM - routing table, arp table, running config, packet buffer

NVRAM - startup config file

Flash - IOS files
ROM - POST, limited IOS (backup), firmware for boot

Question 36

of unique addresses

Answer 36

IPv4 - 4.2 billion
IPv6 - 340 undecillion (10^36)

Question 37

limitations of IPv4

Answer 37

IP address depletion
routing table expansion
lack of end-to-end connectivity (NAT hides device address)

Question 38

metric

Answer 38

how a router decides which route to use if there are two possible routes to the same destination
represents router preference

Question 39

elements of routing table

Answer 39

router source (how router learned network)
destination network
administrative distance
metric
next-hop address
route timestamp
outgoing interface

Question 40

Protocol field

Answer 40

1 byte
indicates data payload type
common values:
ICMP - 1
TCP - 6
UDP - 17

Question 41

administrative distance

Answer 41

trustworthiness of router
lower values mean higher trustworthiness

Question 42

IPv4 - 3 fields used for validation

Answer 42

IHL - Internet Header Length (4 bits)
Total Length (2 bytes)
Header Checksum (2 bytes)