DHCP Operation
DHCP is a client/server protocol used to assign configuration(ip, gateway, dns, options etc.) to hosts dynamically. It is an extension of BOOTP protocol and backward compatibility is maintained. DHCP essentially uses BOOTP message format added with some options filed using UDP(Port 67 & 68). Clients/Hosts send request to DHCP servers for IP address and Server respond with a free IP address from it’s IP pool. A IP Pool is a contiguous range of IPs allocated for DHCP use. Server/Client perform the sanity check for the IP offered/allocated by sending a ARP request. Server also inform the client about how much time it can use the allocated IP, it’s called lease duration. Once the lease duration is expired, a client can extend the lease by requesting a renew of that address from the server. DHCP Message Formats In a general scenario DHCP mainly uses Discover, Offer, Request and Acknowledge messages, it’s […]
Tags   dhcp dhcp ack dhcp discover dhcp lease dhcp offer dhcp reuest dhcp transaction id dhcpdecline dhcpinform dhcpnak dhcprelease dora 
Gratuitous ARP & Proxy ARP