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Which DHCP message type is sent first in the process of obtaining an address lease?
DHCPREQUEST
What is the correct order in which the DHCP message types are successully initial in a IP address?
Dhcpdiscover, dhcpoffer, dhcprequest, dhcppack
What is dhcpack?
DHCPACK is a confirmation for the acceptance of the DHCPOFFER from the Client. DHCP Server Sends DHCPACK in response to DHCPREQUEST to renew the lease time or to confirm the allocated IP address. DHCPACK is a confirmation for the acceptance of the DHCPOFFER from the Client. DHCP Server Sends DHCPACK in response to DHCPREQUEST to renew the lease time or to confirm the allocated IP address.
How does the DHCP client respond to the DHCP server?
Below are the steps how DHCP Client/Server relationship works.IN the network the clicent device requests a packets to DHCP server to login to the network. This Packet known as DHCPDiscover.The DHCP Server receives that packet and in responce it sends a packet to the client, this is called as DHCPOffer. This DHCPOffer packet contains unleased or unused list of IP(Internet Protocol) addresses over the LAN.The DHCP Client receives the DHCPOffer from DHCP Server and responds. This is called DHCPRequest, and this request contains the accepted IP address in the DHCPOffer it received from DHCP Server.Now the DHCP Server receives the DHCPRequest and sends back the DHCPPackets and lets clients to access network.
What is the purpose of lease obtained?
The purpose of the Lease Obtained is to give you a "Temporary" IP Address that will change when the lease Expired date comes close. EX: (Lease Obtained: Sunday October 18, 2012 at 12:30:15 PM / Lease Expires: Friday November 12, 2012 at 10:45:55 AM) "The client starts to renew a lease when half of the lease time has passed. For example, for a 24 hour lease, the client will attempt to renew the lease after 12 hours. The client requests the renewal by sending a DHCPREQUEST message to the server. The renewal request contains the current IP address and configuration information of the client."
What is Dora process in DHCP and how it works?
1) Client makes a UDP Broadcast to the server with a DHCPDiscover, or Discover packet. 2) DHCP offers to the client. The server sends a DHCPOffer including other configuration parameters (DHCP Options) for the client per the servers configuration file 3) In response to the offer Client requests the server. The client replies DHCPRequest, unicast to the server, requesting the offered address. 4)The server sends DHCPAck acknowledging the request which is the clients final permission to take the address as offered. Before sending the ack the server double checks that the offered address is still available, that the parameters match the clients request and (if so) marks the address taken. A good reference for DHCP information is Droms and Lemon "The DHCP Handbook". BoydK
Which type of server assigns ip addresses to clients on a temporary or lease basis?
The DHCP server (Dynamic Host Configuration Protocol)What is DHCP?Dynamic Host Configuration Protocol (DHCP) is a network protocol that enables a server to automatically assign an IP address to a computer from a defined range of numbers (i.e., a scope) configured for a given network. DHCP assigns an IP address when a system is started, for example:A user turns on a computer with a DHCP client.The client computer sends a broadcast request (called a DISCOVER or DHCPDISCOVER), looking for a DHCP server to answer.The router directs the DISCOVER packet to the correct DHCP server.The server receives the DISCOVER packet. Based on availability and usage policies set on the server, the server determines an appropriate address (if any) to give to the client. The server then temporarily reserves that address for the client and sends back to the client an OFFER (or DHCPOFFER) packet, with that address information. The server also configures the client's DNS servers, WINS servers, NTP servers, and sometimes other services as well.The client sends a REQUEST (or DHCPREQUEST) packet, letting the server know that it intends to use the address.The server sends an ACK (or DHCPACK) packet, confirming that the client has a been given a lease on the address for a server-specified period of time.
What server gives the PC its subnet mask and default gateway?
a dhcp server.............What is DHCP?Dynamic Host Configuration Protocol (DHCP) is a network protocol that enables a server to automatically assign an IP address to a computer from a defined range of numbers (i.e., a scope) configured for a given network.DHCP assigns an IP address when a system is started, for example:A user turns on a computer with a DHCP client.The client computer sends a broadcast request (called a DISCOVER or DHCPDISCOVER), looking for a DHCP server to answer.The router directs the DISCOVER packet to the correct DHCP server.The server receives the DISCOVER packet. Based on availability and usage policies set on the server, the server determines an appropriate address (if any) to give to the client. The server then temporarily reserves that address for the client and sends back to the client an OFFER (or DHCPOFFER) packet, with that address information. The server also configures the client's DNS servers, WINS servers, NTP servers, and sometimes other services as well.The client sends a REQUEST (or DHCPREQUEST) packet, letting the server know that it intends to use the address.The server sends an ACK (or DHCPACK) packet, confirming that the client has a been given a lease on the address for a server-specified period of time.When a computer uses a static IP address, it means that the computer is manually configured to use a specific IP address. One problem with static assignment, which can result from user error or inattention to detail, occurs when two computers are configured with the same IP address. This creates a conflict that results in loss of service. Using DHCP to dynamically assign IP addresses minimizes these conflicts.
What is the dhcpnack and when do you get one name 2 scenarios?
Recently I saw a lot of queries regarding when the Microsoft DHCP server issues a NAK to DHCP clients.For simplification purposes, I am listing down the possible scenarios in which the server should NOT issue a NAK. This should give you a good understanding of DHCP NAK behavior.When a DHCP server receives a DHCPRequest with a previously assigned address specified, it first checks to see if it came from the local segment by checking the GIADDR field. If it originated from the local segment, the DHCP server compares the requested address to the IP address and subnet mask belonging to the local interface that received the request.DHCP server will issue a NAK to the client ONLY IF it is sure that the client, "on the local subnet", is asking for an address that doesn't exist on that subnet.The server will send a NAK EXCEPT in the following scenarios:-1. Requested address from possibly the same subnet but not in the address pool of the server:-This can be the failover scenario in which 2 DHCP servers are serving the same subnet so that when one goes down, the other should not NAK to clients which got an IP from the first server.2. Requested address on a different subnet:-If the Address is from the same superscope to which the subnet belongs, DHCP server will ACK the REQUEST.The DHCPNACK or Negative Acknowledgment is a packet that the server sends if the IP address is not available in stand of DHCPACK (in use on other client for example) or the address is no longer valid. In case of DHCPNACK the client must restart the lease process in order to get an IP address.
Describe the steps taken by the client and DHCP server in order to obtain an IP address?
Firstly, a DHCP server is needed which distributes the IP addresses. This machine will serve as a base for all DHCP requests and must also have a fixed IP address. Therefore, on a network there can only be one machine with a fixed IP address, the DHCP server.The basic communication system is BOOTP (with UDP frame). When a machine is turned on, it has no information on its network configuration, and there is nothing special that the user needs to do to find an IP address. In order to do this, the technique used is the broadcast: to find and talk with a DHCP server, the machine will simply send a special broadcast packet (broadcast on 255.255.255.255 with other information such as the type of request, the connection ports, etc.) over the local network. When the DHCP receives the broadcast packet, it will send back another broadcast packet (do not forget that the client does not obviously have the IP address and that therefore cannot be connected to directly) containing all the information required for the client.It could be believed that one single packet is enough for the protocol to work. In fact, there are several types of DHCP packets likely to be issued either by the client for the server(s), or by the servers to a client:DHCPDISCOVER (to locate available DHCP servers)DHCPOFFER (server response to a DHCPDISCOVER packet, which contains the initial parameters)DHCPREQUEST (varied request from the client for example to extend its lease)DHCPACK (server response which contains the parameters and IP address of the client)DHCPNAK (server response to indicate to the client that its lease has expired or if the client announces a bad network configuration)DHCPDECLINE (the client announces to the server that the address is already in use)DHCPRELEASE (the client releases its IP address)DHCPINFORM (the client requests local parameters, it already has its IP address)The first packet issued by the client is a DHCPDISCOVER type packet. The server responds with a DHCPOFFER packet, particularly in order to submit an IP address to the client. The client establishes its configuration and then makes a DHCPREQUEST to validate its IP address (a broadcast request since DHCPOFFER does not contain the IP address). The server simply responds with a DHCPACK with the IP address for confirmation of the allocation. Normally, this is enough for the client to obtain an effective network configuration, but it can be longer or shorter according to whether the client accepts the IP address or not.Hope this will help you to understand DHCP.Regards,Jaydeep.Gatlewar@gmail.com
