What is DHCP packet format?
The DHCP employs a connectionless service model, using the User Datagram Protocol (UDP). It is implemented with two UDP port numbers for its operations which are the same as for the bootstrap protocol (BOOTP). UDP port number 67 is the destination port of a server, and UDP port number 68 is used by the client.
What is DHCP offer?
2. DHCP Offer. When a DHCP server receives the DHCP Discover message from the client, it also broadcasts a DHCP Offer message over the Ethernet network (because the client IP address has not been allocated yet), informing the client that it is available.
What options are sent with the DHCP offer?
Common Options
- DHCP option 1: subnet mask to be applied on the interface asking for an IP address.
- DHCP option 3: default router or last resort gateway for this interface.
- DHCP option 6: which DNS (Domain Name Server) to include in the IP configuration for name resolution.
- DHCP option 51: lease time for this IP address.
Is DHCP offer broadcast or unicast?
broadcast
It’s a broadcast. DISCOVER, OFFER, REQUEST, ACK are all broadcast. Client does not get an IP address before the whole process is completed. So it has to broadcast.
Why DHCP offer is broadcast?
The broadcast ensures that all the responding DHCP servers know that the client has chosen a server. The servers that are not chosen can cancel the reservations for the IP addresses that they had offered. The selected server allocates the IP address for the client and stores the information in the DHCP data store.
Are DHCP offers broadcast?
It’s a broadcast. DISCOVER, OFFER, REQUEST, ACK are all broadcast. Client does not get an IP address before the whole process is completed. So it has to broadcast.
Why is the DHCP offer broadcast?
What is a DHCP offer?
DHCP offer. When a DHCP server receives a DHCPDISCOVER message from a client, which is an IP address lease request, the DHCP server reserves an IP address for the client and makes a lease offer by sending a DHCPOFFER message to the client.
What is the format of a DHCP message?
Dynamic Host Configuration Protocol (DHCP) Message Format All Dynamic Host Configuration Protocol (DHCP) messages include a FIXED format section and a VARIABLE format section. The fixed format section consists of several fields that are the same in every Dynamic Host Configuration Protocol (DHCP) message.
What are the different versions of DHCP clients?
Windows NT Workstation versions 3.5, 3.51, and 4.0 Microsoft TCP/IP-32 for Windows for Workgroups versions 3.11, 3.11a, and 3.11b Different DHCP clients support different options that they can receive from the DHCP server. The following Microsoft server operating systems provide DHCP server functionality: Windows NT Server version 3.5
What does the DHCP option field contain?
The DHCP section identifies the packet as an Offer. The YIADDR field is populated with the IP address the server is offering the client. Note the CHADDR field still contains the physical address of the requesting client. Also, we see in the DHCP Option Field section the various options being sent by the server along with the IP address.