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Chapter 2: IP Addressing and Related Topics
TRUE/FALSE
1. IP addresses can be represented as domain
names to make it possible for users to identify and access resources on a
network.
ANS: T PTS: 1 REF: 59
2. As a frame moves from interface to interface,
the IP source and destination address information is preserved.
ANS: T PTS: 1 REF: 59-60
3. Class D addresses always take the following
binary form: bbbbbbbb.11111111.11111111.11111111.
ANS: F PTS: 1 REF: 62
4. When a host uses a service that employs a
multicast address, it registers itself to “listen” on that address, as well as
on its own unique host address (and the broadcast address).
ANS: T PTS: 1 REF: 62
5. Providing a narrower address space is the
primary design goal for IPv6.
ANS: F PTS: 1 REF: 77
MULTIPLE CHOICE
1. To be valid, any domain name must correspond
to at least one unique ____.
|
a.
|
loopback address
|
c.
|
firewall
|
|
b.
|
numeric IP address
|
d.
|
IP gateway
|
ANS: B PTS: 1 REF: 58
2. The ____ address is a six-byte numeric
address, burned into firmware (on a chip) by network interface manufacturers.
|
a.
|
symbolic
|
c.
|
reverse proxy
|
|
b.
|
logical numeric
|
d.
|
physical numeric
|
ANS: D PTS: 1 REF: 59
3. ____ is used to permit computers to translate
numeric IP addresses to MAC layer addresses.
|
a.
|
ARP
|
c.
|
Reverse proxying
|
|
b.
|
RARP
|
d.
|
Subnet masking
|
ANS: A PTS: 1 REF: 59
4. ____ is used to translate MAC layer addresses
into numeric IP addresses.
|
a.
|
ARP
|
c.
|
Reverse proxying
|
|
b.
|
RARP
|
d.
|
Subnet masking
|
ANS: B PTS: 1 REF: 59
5. The term ____ is used to describe the data
frame crossing a router.
|
a.
|
firewall
|
c.
|
loopback
|
|
b.
|
hop
|
d.
|
dot squad
|
ANS: B PTS: 1 REF: 60
6. ____ addresses are used for multicast
communications, in which a single address may be associated with more than one
network host machine.
|
a.
|
Class A
|
c.
|
Class C
|
|
b.
|
Class B
|
d.
|
Class D
|
ANS: D PTS: 1 REF: 61
7. A ____ represents a network address that all
hosts on a network must read.
|
a.
|
loopback
|
c.
|
broadcast address
|
|
b.
|
hop
|
d.
|
dot squad
|
ANS: C PTS: 1 REF: 62
8. A ____ is a special bit pattern that “blocks
off ” the network portion of an IPv4 address with an all-ones pattern.
|
a.
|
reverse proxy
|
c.
|
broadcast address
|
|
b.
|
summary address
|
d.
|
subnet mask
|
ANS: D PTS: 1 REF: 65
9. A(n) ____ is a device that interconnects
multiple IP networks or subnets.
|
a.
|
subnet mask
|
c.
|
layer-3 switch
|
|
b.
|
IP gateway
|
d.
|
network address
|
ANS: B PTS: 1 REF: 67
10. When a computer on one subnet wishes to
communicate with a computer on another subnet, traffic must be forwarded from
the sender to a nearby ____ to send the message on its way from one subnet to
another.
|
a.
|
broadcast address
|
c.
|
subnet mask
|
|
b.
|
IP gateway
|
d.
|
proxy server
|
ANS: B PTS: 1 REF: 67
11. The simplest form of subnet masking uses a
technique called ____, in which each subnet includes the same number of
stations and represents a simple division of the address space made available
by subnetting into multiple equal segments.
|
a.
|
constant-length subnet masking
|
c.
|
dot squad
|
|
b.
|
firewall
|
d.
|
anycast
|
ANS: A PTS: 1 REF: 67
12. One form of subnet masking uses a technique
called ____ and permits a single address to be subdivided into multiple
subnets, in which subnets need not all be the same size.
|
a.
|
IP gateway
|
c.
|
variable-length subnet masking
|
|
b.
|
constant-length subnet masking
|
d.
|
IP renumbering
|
ANS: C PTS: 1 REF: 67
13. ____ gets its name from the notion that it
ignores the traditional A, B, and C class designations for IP addresses and can
therefore set the network-host ID boundary wherever it wants to, in a way that
simplifies routing across the resulting IP address spaces.
|
a.
|
Route aggregation
|
c.
|
NAT
|
|
b.
|
Address masquerading
|
d.
|
Classless Inter-Domain Routing
|
ANS: D PTS: 1 REF: 68
14. ____ allows IPv4 addresses from Class A, B,
or C to be combined and treated as a larger address space, or subdivided
arbitrarily, as needed.
|
a.
|
Supernetting
|
c.
|
Subnet masking
|
|
b.
|
Classless Inter-Domain Routing
|
d.
|
Address masquerading
|
ANS: B PTS: 1 REF: 69
15. ____ may be performed by boundary devices
that include proxy server capabilities to replace private IP addresses with one
or more public IP addresses as outbound traffic exits the server, and to
replace such public addresses with their proper private equivalents as incoming
traffic passes through the server.
|
a.
|
IP renumbering
|
c.
|
Address masquerading
|
|
b.
|
Supernetting
|
d.
|
Subnetting
|
ANS: C PTS: 1 REF: 70
16. One of the most important services that a
____ provides is to manage what source addresses appear in outbound packets
that pass through it.
|
a.
|
loopback
|
c.
|
subnet mask
|
|
b.
|
proxy server
|
d.
|
layer-3 switch
|
ANS: B PTS: 1 REF: 72
17. RFC ____ reserves three ranges of IP
addresses for private use - a single Class A (10.0.0.0–10.255.255.255), 16
Class Bs (172.16.0.0–172.31.255.255), and 256 Class Cs
(192.168.0.0–192.168.255.255).
|
a.
|
1517
|
c.
|
1878
|
|
b.
|
1518
|
d.
|
1918
|
ANS: D PTS: 1 REF: 76
18. ____ lets networks use multiple private IPv4
addresses internally and maps them to one or more public IPv4 addresses
externally.
|
a.
|
DNS
|
c.
|
NAT
|
|
b.
|
IP gateway
|
d.
|
VoIP
|
ANS: C PTS: 1 REF: 76-77
19. Multicast addresses in IPv6 use a(n) ____ to
define the portion of the Internet to which the multicast group pertains.
|
a.
|
scope identifier
|
c.
|
loopback identifier
|
|
b.
|
interface identifier
|
d.
|
aggregatable global unicast address
|
ANS: A PTS: 1 REF: 80
20. Previously, IPv6 specified that interface
identifiers followed the modified ____ format, which specifies a unique 64-bit
interface identifier for each interface.
|
a.
|
RFC 4941
|
c.
|
EULA-64
|
|
b.
|
EUI-64
|
d.
|
IEEE 802.64v6
|
ANS: B PTS: 1 REF: 80
21. In IPv6, the ____ address is all zeroes and
can be represented as two colon characters (::) in normal notation.
|
a.
|
anycast
|
c.
|
multicast
|
|
b.
|
broadcast
|
d.
|
unspecified
|
ANS: D PTS: 1 REF: 82
COMPLETION
1. The physical numeric address functions at a
sublayer of the Data Link layer in the OSI network reference model, called the
____________________.
ANS:
Media Access Control layer
media access control layer
MAC layer
PTS: 1 REF: 59
2. ____________________ informs the network
interface card to pass packets sent to that address to the IP stack so their
contents can be read, and tells the IP gateway to forward such traffic onto the
physical network, where the listening network interface resides.
ANS: Registration
PTS: 1 REF: 62-63
3. The activity of stealing (borrowing) bits
from the host portion to further subdivide the network portion of an address is
called ____________________.
ANS:
subnetting
subnetting a network address
PTS: 1 REF: 66
4. ____________________ combines contiguous
network addresses by stealing bits from the network portion and using them to
create a single, larger contiguous address space for host addresses.
ANS: Supernets
PTS: 1 REF: 67
5. In IPv6, _________________________ addresses
are used to send an identical message to multiple hosts.
ANS: multicast
PTS: 1 REF: 83
MATCHING
Match each item with a statement below.
|
a.
|
Solicited node address
|
f.
|
Secure end-to-end connection
|
|
b.
|
Anycast address
|
g.
|
ICANN
|
|
c.
|
Class E addresses
|
h.
|
Application specific integrated circuits
|
|
d.
|
255.0.0.0
|
i.
|
Layer 3 switching
|
|
e.
|
255.255.255.0
|
|
1. used by switches to make decisions
2. packets goes to the nearest single instance
of this address
3. default mask for Class A networks
4. allows IP traffic to move in encrypted form
between the sender and receiver without intermediate translation.
5. manages all IP-related addresses, protocol
numbers, and well-known port addresses, and also assigns MAC layer addresses
for use in network interfaces
6. default mask for Class C networks
7. special type of multicast address used to
support Neighbor Solicitation (NS)
8. allows you to partition a large network into
many smaller subnets, with almost no loss of performance
9. used for experimental purposes only
1. ANS: H PTS: 1 REF: 74
2. ANS: B PTS: 1 REF: 84
3. ANS: D PTS: 1 REF: 65
4. ANS: F PTS: 1 REF: 70-71
5. ANS: G PTS: 1 REF: 73
6. ANS: E PTS: 1 REF: 65
7. ANS: A PTS: 1 REF: 83
8. ANS: I PTS: 1 REF: 74
9. ANS: C PTS: 1 REF: 61
SHORT ANSWER
1. Briefly discuss IPs three-part addressing
scheme.
ANS:
Logical numeric: This consists of a set of four numbers,
separated by periods, as in 172.16.1.10.Each of these four numbers must be
smaller than 256 in decimal to be represented in eight binary digits, or bits.
Physical numeric:This consists of a six-byte numeric
address, burned into firmware (on a chip) by network interface manufacturers.
PTS: 1 REF: 58-59
2. Why are concepts such as subnets and
supernets important for TCP/IP networks?
ANS:
The reason concepts like subnets and supernets are important for TCP/IP
networks is that each of these ideas refers to a single “local neighborhood” on
such a network, seen from a routing perspective. When network addresses are
further subdivided beyond their defaults for whatever class to which an address
belongs, such subnetting represents “stealing bits” (borrowing bits) from the
host portion of the address and using those stolen (borrowed) bits to create
multiple routing regions within the context of a single network address.
PTS: 1 REF: 66
3. Briefly describe how to calculate subnet
masks.
ANS:
There are several varieties of subnet masks that you can design for a
network, depending on how you want to implement an address segmentation scheme.
The simplest form of subnet masking uses a technique called constant-length
subnet masking (CLSM), in which each subnet includes the same number of
stations and represents a simple division of the address space made available
by subnetting into multiple equal segments.
Another form of subnet masking uses a technique called variable-length
subnet masking (VLSM) and permits a single address to be subdivided into
multiple subnets, in which subnets need not all be the same size.
PTS: 1 REF: 67
4. What are the limitations of creating a CIDR
address?
ANS:
1. All the addresses in the CIDR address must be contiguous. Use of the
standard network prefix notation for addresses,however, also makes it tidy and
efficient to carve up any kind of address, as needed.
2. When address aggregation occurs, CIDR address blocks work best when
they come in sets that are greater than 1 and equal to some lower-order bit
pattern that corresponds to all 1s - namely in groups of 3, 7, 15, 31, and so
on. That’s because this makes it possible to borrow the corresponding number of
bits (two, three, four, five,and so on) from the network portion of the CIDR
address block and use them to extend the host portion instead.
3. To use a CIDR address on any network, all routers in the routing
domain must “understand” CIDR notation. This is typically not a problem for
most routers that were built after September 1993, when RFCs 1517, 1518, and
1519 were approved, because most router vendors began to support CIDR addresses
at that time.
PTS: 1 REF: 69
5. What are the disadvantages of using private
IP addresses?
ANS:
The disadvantages are:
Such addresses may not be routed across the public Internet.
Some IP services require what’s called a secure end-to-end connection
- IP traffic must be able to move in encrypted form between the sender and
receiver without intermediate translation. Thus, if either party to such a
connection uses a public IP address, it’s easiest to configure if both parties
use a public IP address because the address for the “private end” of the
connection cannot be routed directly across the Internet.
PTS: 1 REF: 70-71
6. Most organizations need public IP addresses
only for two classes of equipment. Briefly describe each of these classes.
ANS:
Devices that permit organizations to attach networks to the Internet.
These include the external interfaces on boundary devices of all kinds, such as
routers, proxy servers, and firewalls, that help maintain the perimeter between
the “outside” and “inside” on networks.
Servers that are designed to be accessible to the Internet. These
include public Web servers, e-mail servers, FTP servers, news servers, and
whatever other kind of TCP/IP Application layer services an organization may
want to expose on the public Internet.
PTS: 1 REF: 71
7. List the constraints that determine the
number and size of networks.
ANS:
These are:
Number of physical locations
Number of network devices at each location
Amount of broadcast traffic at each location
Availability of IP addresses
Delay caused by routing from one network to another
PTS: 1 REF: 73
8. Give two reasons why you should use binary
boundaries.
ANS:
One reason is that, in the future, you may want to implement layer-3
switching to reduce the broadcast traffic, and if the devices fit in a binary
boundary, you won’t have to readdress them.
Another good reason to use binary boundaries is that one day you will
want to classify your traffic to apply Quality of Service (QoS)
or policies of some sort.
PTS: 1 REF: 75
9. What are some of the design goals for IPv6?
ANS:
Although providing a much larger address space is one of the primary
design goals for IPv6, it is hardly the only reason for implementing IPv6, nor
is this the only change made in the latest version of the IP protocol. IP has
required a number of other important updates besides the lack of available
unique addresses. IPv6 not only provides a vast abundance of IP addresses and
better management of its address space, it eliminates the need for NAT and
other technologies to be put in place to shore up the inadequate number of IPv4
addresses. IPv6 also makes it easier to administer and configure IP addresses.
Also, IPv6 has modernized routing support and natively allows for
expansion
along with the growing Internet.
Finally, IPv6 supports network security by using authentication and
encryption extension headers, among other methods.
PTS: 1 REF: 77
10. How can you express native IPv6 addresses in
URLs?
ANS:
RFC 2732 (originally proposed in 1999) describes a method to express
IPv6 addresses in a form compatible with HTTP URLs. Because the colon character
(:) is used by most browsers to set off a port number from an IPv4 address,
native IPv6 addresses in their ordinary notation would cause problems. This RFC
uses another pair of reserved characters, the square brackets ([ and ]), to
enclose a literal IPv6 address. The RFC indicates that these square bracket
characters are reserved in URLs exclusively for expressing IPv6 addresses. This
RFC is now a standard, which means that this syntax represents the official
format for expressing IPv6 addresses inside URLs.
PTS: 1 REF: 82
