Running head: NETWORKING QUESTIONS
Networking Questions
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Question 1: Benefits and Disadvantages of using Group Policy in an Organization
Group policy is a system within the Active Directory that enables the network
administrators to define user, security and organization wide policies throughout the network.
This is possible because through the group policy, the administrators will be able to define the
options for what the users can do on a network like what files, folders, and applications they can
access and also what users are allowed or not allowed to do on their computers (Stanek, 2013).
The benefits of group policy in an organization are as explained below:
Security- Network security is a major concern for all businesses and thus through group
policy an administrator can restrict unidentified users from remote computers to access the
network resources and also can set minimum requirements for setting of passwords to make them
strong and not easy to guess or crack. This can be attained by requiring the use of both capital,
lowercase letters, numbers and symbols for the password to be accepted in the system.
Ease of management- When the users are connected through group policy, the
management of a network is much easier because it will be possible to implement company-wide
policies as group policy settings will reflect all persons and computers in domain, site and
organizational unit.
Increased productivity- Through group policy settings, the users are no longer confined
to a single work computer because all folders and files with their personalized settings can be
made available on all computers.
Time and cost saving- Through the use of group policy, administrator can
install/update/upgrade software from a single location and thus be able to service every single
computer simultaneously and most importantly the installations and updates can be scheduled to
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occur outside of business hours and in so doing, no one will be interrupted while they are
working.
Roaming profiles- Group policy enable users to have roaming profiles in that if any user
logs into any computer within the network, it loads the settings to which his/her account is
authorized and thus one will be able to access all the resources needed for one to accomplish a
task depending on the account details rather than been tied to a specific computer.
The disadvantages of group policy in an organization are as explained below:
For large networks, organizing a large number of GPOs can become cumbersome as
group policy can become complicated web of OUs, users and devices. In simpler environments,
it can also be difficult to identify which sets of policies apply to which device. Configuration
mistakes can also cause group policy to be ineffective or even not to work at all. Finally group
policies are restrictive and thus in case one wants to lighten the restrictions for one machine
temporarily, the administrator has to find and alter the group policy that controls what he/she
wants to change for that machine. Having to go through such a process within multiple machines
can prove to be a hard task.
Question 2: Policies available in Windows 2012 Server
Group policy is an infrastructure that enables the network administrator to specify
managed configurations for users and computers through group policy preferences. One of the
policies available in windows 2012 server is group policy infrastructure status and it displays the
status of Active Directory and SYSVOL replication as it relates to all group policy objects or a
single group policy object. Basically, group policy relies on being stored and replicated to all
domain controllers in a domain and thus there can be a lag time after a change is made on one
domain controller before the change is replicated to all other domain controllers. Until changes
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to a GPO are replicated to the domain controller that a client is accessing, that particular
computer will receive the earlier version of the GPO during group policy refresh. In earlier
versions of windows operating system, administrators had to download GPOtool.exe to diagnose
these issues but in windows server 2012, an administrator needs not to download and run a
separate tool for monitoring and diagnosing replication issues related to group policy at domain
level. The following details will also be able to be viewed: ACL details, AD and SYSVOL GPO
version details and the number of GPOs listed in AD and SYSVOL for each domain controller.
(Morimoto, 2012)
References
Stanek, W. R. (2013). Microsoft Windows server 2012 inside out. Redmond, Wash: Microsoft
Press.
Morimoto, R., Noel, M., Droubi, O., Abbate, A., Yardeni, G., &Amaris, C. (2012).Windows
Server 2012 unleashed. Indianapolis, IN: Sams.
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Question 3: TCP and UDP and their Differences
Transmission Control Protocol is a standard that defines how to establish and maintain a
network conversation through which application programs can exchange data and it works with
internet protocol that defines how computers send packets of data to each other. It is a
connection oriented protocol which means a connection is established and maintained until the
application programs at each end finish the exchange of messages. User Datagram Protocol is an
alternative communications protocol to TCP that is used primarily for establishing low-latency
and loss tolerating connections between applications on the internet. It is a connectionless
protocol. The major differences are explained below:
Reliability- TCP provides delivery guarantee because if a packet is lost in transit, the
recipient requests for it and the sender retransmits it while UDP is unreliable as it doesn’t
provide delivery guarantee.
Ordering- TCP ensures that all sequencing and ordering is done from the receiving end of
the network even if the packets arrive out of order while UDP doesn’t provide any ordering or
sequence guarantee and thus packets may be received in any order.
Speed- TCP is slow because it has to create a connection, ensure guaranteed and orderly
delivery while UDP is fast because it has not to worry about such factors. Therefore UDP is
more suitable where speed is a priority like online video streaming or telecast.
Congestion or flow control- TCP handles reliability and congestion control as it requires
three packets to set up a socket connection before any user data can be sent while UDP doesn’t
have an option for flow control.
From the differences discussed above, the two protocols have different field of
applications that best suites each capabilities. Since TCP provides delivery and sequencing
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guarantee, it is best suited for applications that require high reliability and transmission time is
not a priority and should be used where one can’t afford to lose any message like in web
browsing, email and file transfer. UDP is widely used for time sensitive applications and also
servers that answer small queries from huge number of clients. UDP is compatible with packet
broadcast and multicast and is commonly used in DNS, VoIP and online games (Comer, 2011).
Question 4: Transition technologies for IPv6
Teredo gives full Ipv6 connectivity for dual stack hosts that are connected to the internet
but which have no direct native connection to an IPv6 network. Teredo also encapsulates IPv6
data into IPv4 UDP packets and successfully operates through most NAT boundaries (Horley,
2014).
Intra- Site Automatic Tunnel Addressing Protocol enables dual stack devices to transmit
IPv6 traffic between each other across an IPv4 backbone. This technology enables new
networking functions while preserving the underlying network as it is. Once an ISATAP
server/router has been set up, only the clients need to be configured to connect to it and thus this
solution enables organizations to deploy a simple and manageable IPv6 within their
infrastructure with little time and effort. It is also advantageous because within a site, only one
ISATAP router is needed and also a user can connect isolated IPv6/IPv4-dualstack hosts to the
IPv6 internet. ISATAP uses IPv4 as non-broadcast multiple access data link layer and performs
neighbor discovery on top of IPv4. Due to the benefits achieved by ISATAP, I will consider
using this technology. This transition technology will be beneficial where an organization wants
to deploy IPv6 as well as maintain compatibility with large existing base of IPv4 hosts and
routers (Horley, 2014).
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From the online article I read, it is discussing about securing the Tunnels. It is argued that
most of the tunneling protocols used to transition between IPv4 and IPv6 do not provide enough
security mechanisms. My view is that one needs to secure the tunnels using ACLs and other
network controls to prevent them from affecting the security of the overall network. Therefore
ACLs should be defined correctly to limit the traffic that can enter and leave tunnels and also
prevent packets with spoofed source address from entering the company network. By ensuring
this, security will be maintained during the transition period.
My organization is planning to undergo IPv6 transition and since we want the IPv4 to coexist with IPv6 for some time, we are considering using a native dual-stack migration. This is
aimed to allow both IPv4 and IPv6 to run simultaneously over the network in order to facilitate
communication between end user devices regardless of the protocol they are equipped for and
also to ensure that there is no disruption of service if a client requests an IPv4 address.
References
Comer, D., & Stevens, D. L. (2011).Internetworking with TCP/IP. Englewood Cliffs, N.J:
Prentice Hall.
Horley, E. (2014). Practical IPv6 for Windows administrators. New York, N.Y.: Apress.
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Question 5: DHCP reservations and static IP addresses
Some network devices like printers and servers require a constant IP address and this can
be achieved by either manually configuring a static IP address or assigning a reservation on the
DHCP server. Reservations are permanent lease assignments that help ensure that a specified
client on a subnet will always have the same IP address. Networked printers, IP camera systems
and network connected HVAC controllers should get IP addresses through reservations because
they need to have the same IP address and the advantages of this over statically configuring the
IP address will be that: In case the network parameters are changed at the DHCP server, the
device configured with reserved IP address will receive the new network parameters when the
device requests renewal of its lease, while to change the network parameters on a device
configured with a static IP address, the changes will have to be made manually (Bigger, 2014).
Another importance of DHCP reservation is that the administrators will have a central
point of reference for all IP address allocations in the organization and this makes it easy to track
down particular clients or reassigning new scopes. Servers can also use DHCP reservations and
function appropriately although having a static IP address can help ensure that if the router dies,
the server will keep going and clients that still have valid DHCP lease keep working properly
before the problem can be fixed.
Question 6: DHCP Messages Exchanged during Initial Lease Request
DHCP servers and clients communicate through a series of DHCP messages and to
obtain a lease, the DHCP client initiates a conversation with a DHCP server using a series of
these messages:
DHCP Discover- The DHCP client will request an IP address by broadcasting a DHCP
Discover message to the local subnet.
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DHCP Offer- In our case, I assume the DHCP server will be down for around 30 seconds.
The client will send DHCP Discover messages at intervals of 0,4, 8, 16 and 32 seconds until it
finally receives a DHCP offer message from the DHCP server when the server will be up. If for
some case the server could be down for more than a minute, the client will use APIPA to selfconfigure an IP address for its interface or if the client does not support alternate configuration or
it is disabled, the network initialization will fail and in both cases, the client will begin a new
cycle of DHCP discover message every five minutes using the same intervals of 0,4, 8, 16 and 32
seconds up to when the server able to respond.
DHCP Request- The client will indicate the acceptance of the offer by selecting the
offered address and broadcast a DHCP Request message in response.
DHCP Ack- The client will be assigned the IP address and the DHCP server will
broadcast a DHCP Ack message in response and thus finalizing the terms of the lease.
When the client will receive the acknowledgement, it will configure its TCP/IP properties
by using the DHCP option information in the reply and thus completing its initialization of
TCP/IP (Droms, 2014).
The diagram is as shown below for the above discussed IP address lease process:
DHCP Lease Process Overview
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References
Bigger, D. (2014). CompTIA Network+ 2014: Configuring DHCP.
Droms, R., & Lemon, T. (2014).The DHCP handbook: Understanding, deploying, and managing
automated configuration services. Indianapolis, IN: Macmillan Technical Pub.