A plus 220-1001 – Exam Objective 2.6 – Dumps4shared

A plus 220-1001 – Exam Objective 2.6

A+ Exam Objective 2.6

2.6 Explain common network configuration concepts.

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Here we will solidify the concepts covered in A+ 220-1001 sub-objective 2.6 “Explain common network configuration concepts”. We will look at the properties that make TCP/IP the robust protocol set that it is and how TCP/IP is used to manage networks from the smallest of LANs all the way up to the World Wide Web.

IP Addresses

The TCP/IP protocol stack is the foundation of the World Wide Web
and most local networks. Each host or client connecting to a network such as
the Web needs a unique address. Duplication of addresses causes a failure of
one or both hosts.

The IP protocol is used for host identification. There are two
types of IP addresses being actively used: IPv4 and IPv6. The original
addressing organization was IPv4 which, while still heavily used today, has exceeded
its capacity to serve the rapidly growing number of internet connected
computers and devices. In 1999, the IANA (Internet Assigned Numbers Authority)
began the deployment of the IPv6 protocol.


An IP address consists of 32-bits, separated using a dotted
decimal notation into four octets with dots (periods). The numbers are assigned
in binary, where you could see a number like
11011111.10110010.10011011.00000011. For each octet, the maximum value is 255
(all 1’s in binary). The binary number is then converted into decimal numbers
that are easier for humans to recognize. The example above would translate to a
decimal value of

Each octet can assign eight binary values of zero or one. A good
way to verify that your TCP/IP protocol stack has been correctly installed with
a new network card is by pinging its loopback address. The IPv4 address is and by pinging this, you can check the installation and functionality
of the interface.

Loopback IPv4 and IPv6


In order to address the inevitable exhaustion of IPv4 addresses,
the deployment of IPv6 began in 1999, providing 340 undecillion or 340,282,366,920,938,463,463,374,607,431,768,211,456
addresses. The IPv6 address is 128-bits in length and although it is actually a
binary address, the use of a 128-bit binary address is impractical for human
interpretation. Instead, the IPv6 is expressed in hexadecimal numbers separated
by colons and consists of eight groups of hexadecimal values. Hexadecimal
numbering allows for up to 16 case sensitive values (0-9 and A-F) to be
expressed for each digit as opposed to the standard base 10 decimal system.
Each hexadecimal digit represents four digits or bits of binary. Each of the
eight groups of an IPv6 address represents 16 bits (Two four bit values). A
typical IPv6 address will look something like this,
2002:1F93:AF34:DA4C:0000:0000:0000:CADE. For IPv6, the loopback function is the
same as IPv4 using an IPv6 address. This address is represented as 0::1 or even
simply ::1.

In IPv6 shorthand notation, groups of zeroes are represented by double
colons. Our example can be written as 2002:1F93:AF34:DA4C:: CADE. Note that the
double colons substituted for three groups of zeroes. Only one set of colons is
allowed in an IPv6 address. Here, the binary value of the first block would be
0010 0000 0000 0010. The Interface Identifier or node address is represented by
the last 64-bits of the 128-bit address. In our example, the node is identified
as 222 or binary 11011110.

IPv6 prefix

Public and Private

The IANA has reserved the following address ranges for private
networks. The address ranges are listed below. The best example of private
network deployment is with SOHO or at home where you are provided a single,
public IP address from an internet service provider (ISP) and use NAT/PAT to
assign private numbers to use the public address for computers and phones.


The IANA has reserved the following address ranges for private
networks. This means any address within these ranges is private and
non-routable. – – –


The address block of fc00::/7 is reserved by IANA for private
use as Unique Local Addresses (ULA). This means that the first block assigned
will be fd00::/8.

APIPA/link local

Best described as Zero configuration networks, APIPA and link
local addresses are assigned to hosts when there is no reachable DHCP server
and there is no manual address assignment. IPv4 uses the address range
to and IPv6 uses the block fe80::/64, in other words the address
fe80 and enough zeroes to make 64 bits. You may see a % sign followed by a
number in the IPv6 link local address. This is a Zone ID network identifier.
This is useful as many computers have wired and wireless connections. Each NIC
or device on a network segment is given an ID to determine which interface to
send particular traffic out on. APIPA and link local addresses are

Client-side DHCP vs
Static Addressing

The most common IPv4 or IPv6 TCP/IP addressing method is DHCP (Dynamic
Host Configuration Protocol). On a work network, there is usually an assigned
DHCP server. Residential or SOHO implementations use the router provided by the
ISP to perform this function. DHCP assigns or leases a unique IP address to
each host. The duration of the lease is determined by the network administrator,
otherwise is weekly by default. DHCP will define the internet gateway and
Domain Name Server to be used. This means that your machine may not get the
same IP address when rebooted or otherwise disconnected, however the DNS and
Gateway settings will remain.

The DHCP server has an available pool of addresses available to
assign to clients (hosts) that attempt to connect to the network. The client
broadcasts a UDP discovery packet for an address to all connected networks. All
DHCP servers will offer an address to the client. The client will accept the
offer from the nearest server by requesting a lease and that server will lease
that address to the client. 

The address assignment process is identical for both IPv4 and
IPv6 addressing and only the address format will be different. This greatly
simplifies network management as the other option is Static IP addressing.
Should you need a client to maintain a specific IP address, you can create a
DHCP reservation in order to hold that address permanently.

Manual configuration of IP in Windows

Static IP addressing is preferable for Web servers and Internet
gateways where you would like to be able to consistently locate the machine.
Any device that is accessed consistently by users should be statically
addressed. Otherwise and depending on the size of the network, this would be an
incredibly labor intensive task that would require documentation to avoid
duplication of addresses. If it isn’t memorized, look up the Gateway and DNS
servers on a neighboring machine.

Gateways and DNS

If known, network clients can access computers on the local
network or internet using its IP address. Internet access is dependent on the
configuration of the Gateway on the network, a device that handles off network
requests and forwards them to the internet. The address of this device is part
of the client configuration as is the DNS server address.

It is improbable that the average person knows the IP address of
the sites they wish to visit or even devices or machines on the network. Name
resolution solves this problem by using a DNS (Domain Name Server) to resolve
the IP addresses into names. A DNS server maintains a list machines along with
their IP addresses and their domain names. For example, a DNS server would have
an entry that read www.mysite.com = With that information, any
user can type in the address using the domain name and the server will look it
up and translate the address. If the name is not known to the server, it will
request it from the other DNS servers known to it. Once a device successfully
connects, this information is cached locally. Don’t forget that a Default
Gateway and a DNS Server must be configured in order for your settings to work

ipconfig all

Subnet mask vs.

The original IPv4 design divided the 32-bit address into four 8-bit
groups where each group had a maximum value of 255. In the original IPv4 design,
the network number field was allotted the first eight bits of the address,
representing the network. The remaining 24 bits (the rest) are used to identify
the host. While it could support over 4 billion devices, this format could only
support 254 networks and was quickly deemed insufficient. A solution was needed
to create more networks in order to support the rapidly growing number of LANs
as internet and business networks were proliferating. A quick solution was


Subnet masks were devised to allow more of the 32-bit address to
be used to identify networks. This addressing scheme allows a second set of
numbers, in eight bit blocks that used to be called classes, to identify how
many bits of the address are used to identify the network. The subnet mask is 32-bits
long and formatted in the same way as the IP address. This allows us to use 16-bits
or more for the network address.

The 16-bit mask will use all 1’s for the first 16-bits for the
network address, giving you a hexadecimal representation of
11111111.11111111.00000000.00000000. The zeroes in this example are available
for host identification. In dotted decimal notation, this is written as

24-bit subnet masks are prevalent in SOHO and residential
deployment, giving a subnet mask of Subnet masks are a quick and
painless way to provide more networks. However the only drawback is quite significant
as switching from a 24-bit subnet mask, providing 254 hosts and one subnet, to
a 16-bit subnet allows 65534 hosts on one subnet. This is wasteful in most
cases and only partially addresses the problem.


A Virtual Private Network (VPN) provides networks with an
added layer of security by establishing secure encrypted connections over the
public network in order to protect network traffic from eavesdropping or modification.


Virtual LANs (VLAN) can combine multiple networks into a
single VLAN, making administration easier because the VLAN appears as a simple
LAN. A LAN can also be configured with VLANs in order to isolate departments within
an organization.


Network Address Translation (NAT) enables a router to assign
private IP addresses to multiple clients while appearing externally (publicly)
as a single address. This one-to-many method represents the majority of NAT

And that wraps up our ExamNotes for A+ Sub-objective 2.6. Good luck on the exam!

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