In the early days of computers, administrators would have to assign IP addresses manually to computers and network devices. The current best practice is to use something called the dynamic host configuration protocol DHCP allows a host to obtain or be allocated an IP address. A network administrator can configure. A given host receives the same IP each time it connects to the network or maybe assigned a temp that will be different each time the hose connects to the network. In addition to the host IP address assignment. Supposed to learn additional information such as its subnet mask the address to its often called the first-hop router (called the Gateway) and your address for the local DNS server.
Because DHCP can automate the network-related aspects of connecting a hose to a network it's often returned referred to as a plug-in-play protocol. It makes it very attractive to the network administrator who would otherwise have to perform these tasks manually! DHCP is also enjoying widespread use in residential internet access networks Enterprise networks and in Wireless Lans where host join and leave the network frequently. Consider for example the student who carries a laptop from a dormitory room to a library to a classroom. It is likely than in each location the student will be connecting to a new subnet and hence will need a new IP address at each location. DHCP is ideally suited to the situation, how many users coming in the dresses are needed only for a limited amount of time. The value of D hcp's plug-and-play capability makes it unimaginable that a system administrator would be able to reconfigure laptops at each location, students except those taking a computer networking class would have the expertise to configure their laptops manually.
DHCP is a client-server protocol. Client is typically a newly arriving host wanting to obtain network configuration information, an IP address. In the simplest case, subnet in the addressing sense of figure four. Will have a DHCP server. If no server is present on the subnet, aC. Knows the address of a DHCP server for that network is needed. In our discussion below will assume that a DHCP server is available on the subnet. For a newly arriving host, hcp protocol is a four-step as shown in figure 4.3 for the network settings shown in Figure Four Points in this figure Yia. Indicates the address being allocated to the newly-arrived and client.
Four steps are. Discovery, DHCP server offer, DHCP request, DHCP ack.
Discovery: The first task of a newly arriving host is to find a DHCP server with which to interact. This is done using a DHCP discover message, in which a client sends a UDP packet to Port 67. The UDP packet is encapsulated in IP datagram. But to whom should the state of Granby send? the client doesn't even know the IP address of the network to which it is attaching much less the address of the DHCP server for this network. Given this, the client creates an IP datagram containing its dHCP discover message along with the broadcast identity of 255.255.255.255. And this host Source IP address of zero. 0.0.0.0. The DHCP client passes the IP datagram to the link layer then broadcasts this Frame to all nodes attached to the subnet.
Offer: A DHCP server receiving a DHCP discover message response to the client with a DHCP offer message that is broadcast to all nodes on the subnet again using the IP broadcast address of 255.255.255.255. Send several. Can't be present on the subnet the client may find itself in the inevitable position of being able to choose from among several offers each server offer message contains the transaction ID of the receive discover message the purple for the client the network mask and an IP address lease Time Dash out of time for which the IP address will be valid it is, set the lease time to several hours or days.
Request: The newly arrived choose from among one or more server offers and respond to its selected offer with a DHCP request message at going back the configuration parameters.
Ack: The server response to the DHCP request message with a DHCP ack message confirming the requested parameters.
In Windows, to create a new dHCP server open the DHCP console. Underneath your server name right click on ipv4 and select new scope. The new scope wizard will appear. Give the scope a name. Give the scope a description. Give the scope a start and end IP address. Define the subnet mask length. For a class C address we will use a mask of 24. Click next. Add any exclusions that may be needed. Define your lease duration. This is chosen by how long your clients will be attached to that particular Network. Choose if you wish to configure.. Usually you will choose to configure these options click next. After clicking next you can Define the default gateway for your network. Define the Gateway and click add. Click next you have the ability to Define DNS servers. Define the servers and add them to the list. Click next. If using winds Define it here. Click next. When asked if you want to activate the scope choose yes or no. Click next. Click finish.
If you wish to make reservations for specific clients. Expand the scope you just created. Click on reservations. Right-click rezerve choose new reservation. The reservation name should be the computer name. The IP address is the address you wish to assign to that client. The MAC address is from the machine you wish to assign the address to. The description is used to help you remember later why you define to this reservation. Click add.
If you wish to add additional scope options you may do this. Right click scope choose configure options. You will see a long list of options that you can configure for your da. Choose the options you need to configure and fill in the appropriate detail when finished click okay.
