Win 7
John_matt
replies_needed_comp.docxReply needed 1
I believe that DHCP reservation has its advantages over static IP. Using DHCP reservations help administrators by offering a centralized reference point for all IP allocations. It allows them to assign these reservations and check the status of them from a single point instead of having to log on administratively to a specific machine to set a static IP address. DHCP reservations also make it easier if you plan on moving a printer to different network. You only have to log on and change the subnet in DHCP and it will automatically move all devices to the new subnet. DHCP reservation is basically the same concept of setting a static IP on a device but just adds the convenience factor. In some of the research I have done people recommended that the actual server itself be set with a Static IP then set a DHCP scope and reservations for specific connected devices.
The only downfall to setting reservations is that you must know the MAC address of the said device. Although this is something easy to figure out, it can sometimes become a little repetitive if you have to acquire the MAC for each device. In all though, DHCP reservation has the potential to be a very useful function for administrators who need to allocate specific IPs with specific devices and do not have physical contact with each device.
BIBLIOGRAPHY:
(n.d.). Networking, VPN, TS, Remote Access and Internet Troubleshooting. Retrieved July 25, 2016, from http://www.chicagotech.net/netforums/viewtopic.php?f=1&t=4332
(n.d.). Advantages of DHCP Reservation over Static IP Assignment. Retrieved July 25, 2016, from http://support.microsoft.com/en-us/kb/170062
Reply needed 2
Manually assigning static IP addresses is a very straightforward process. An administrator logs into each of the devices on the network and assigns a static IP address that will be used until someone else manually reconfigures it again. The problem with this method arises when the network becomes midsize or larger. It would be really challenging for an administrator to individually assign and manage hundreds or maybe even thousands of IP addresses, subnet masks, default gateways, and all other configuration options.
In large networks a preferable solution would be to use DHCP reservations, except one caveat. For mission critical systems it would much safer to use static IPs for the reason that with a reservation in DHCP, the client device will still go through the DHCP process to get an the IP which can come at a cost if the DHCP server goes “down”. From the security standpoint, the network becomes more vulnerable to the man in the middle attack. An attacker could setup a rogue DHCP server and redirect all traffic to a different router that is under that attacker’s control.
I think, like any other technology, DHCP reservations have its pros and cons. It allows the administrators to manage the IP assignment process from one central location as well having a complete list of active leases and reservations readily available. The downside is that the initial configuration still requires manual interaction in terms of getting the MAC address for the device.
With all of the mentioned above, for non-vital systems such as printers, cameras, application servers I would definitely use DHCP reservations for ease of management. For mission critical servers I would go static and exclude those IPs from the main scope.
References
Panek, Will & Wentworth, Tylor & Chellis, James. ( © 2008). Mcts: windows server 2008 network infrastructure configuration (exam 70-642). [Books24x7 version] Available from http://common.books24x7.com.ezproxy.umuc.edu/toc.aspx?bookid=25194.
Reply needed 3
Overview of the DHCP Lease Process when a DHCP Server is Unavailable
1. The DHCP client will initiate a request for an IP address when it first attempts to connect to the network. The client will broadcast a DHCPDiscover message to the local subnet requesting IP address information from a DHCP server.
2. If, for whatever reason, the DHCP server does not respond to the client’s request, the client will continue to send DHCPDiscover messages using a randomized exponential backoff algorithm. Subsequent messages will be sent at 4, 8, 16, 32, and 64 seconds with a random interval of plus or minus 1 second.
3. If after one minute (64 seconds) there is no response from a DHCP server, the client will continue with an alternate configuration, such as Automatic Private IP Addressing (APIPA). APIPA is a common alternate configuration where the client will self-configure an IP address in the range of 169.254.0.1 to 169.254.255.254 and a subnet mask of 255.255.0.0 and use this for its interface until DHCP is available. If an alternate configuration is not supported or IP auto-configuration has been disabled, the client network initialization will fail, there will be no network access, and an error message will be generated.
4. In either case, the client will begin a new cycle of DHCPDiscover messages every five minutes using the 0, 4, 8, 16, 32, and 64 second intervals randomized with a plus or minus 1 second interval. It will continue broadcasting these messages every five minutes in this manner until it receives a DHCPOffer message from a DHCP server.
6. The client will indicate acceptance of the offer by broadcasting a DHCPRequest message. This message contains the IP address from the DHCPOffer selected, but it is not yet being used by the client. Until it receives a DHCPAck message from the DHCP server, the client does not officially have an IP address.
7. Finally, the DHCP server will acknowledge the DHCPRequest message by broadcasting a DHCPAck message. This message assigns the address to the client and finalizes the terms of the lease. It is at this point that the client can use the leased IP to configure its TCP/IP properties, complete its initialization, and connect to the network.
Citations:
· How DHCP Technology Works. (2003, March 28). Retrieved from https://technet.microsoft.com/en-us/library/cc780760(v=ws.10).aspx
· Droms, R. (1997, March). RFC2131 - Dynamic Host Configuration Protocol. Retrieved from https://www.ietf.org/rfc/rfc2131.txt
· Kozierok, C. (2005, September 20). DHCP Message Generation, Addressing, Transport and Retransmission: Retransmission of lost messages. Retrieved from http://www.tcpipguide.com/free/t_DHCPMessageGenerationAddressingTransportandRetrans-3.htm
