Editing Dynamic Host Configuration Protocol (section)

===Request===
In response to the DHCP offer, the client replies with a DHCPREQUEST message, broadcast to the server,{{Efn|name="optional-unicasts"|As an optional client behavior, some broadcasts, such as those carrying DHCP discovery and request messages, may be replaced with unicasts in case the DHCP client already knows the DHCP server's IP address.{{Ref RFC|2131}}{{rp|section=4.4.4}}}} requesting the offered address. A client can receive DHCP offers from multiple servers, but it will accept only one DHCP offer.

The client must send the ''server identification'' option in the DHCPREQUEST message, indicating the server whose offer the client has selected.{{Ref RFC|2131}}{{rp|Section 3.1, Item 3}} When other DHCP servers receive this message, they withdraw any offers that they have made to the client and return their offered IP address to the pool of available addresses.
{{APHD|start|title=Example Ethernet frame with a DHCPREQUEST message}}
{{APHD|0|bits1=32|border1=bottom|field1=Source MAC|value1={{MACaddr|00:05:3c:04:8d:59}}}}
{{APHD|4|bits1=16|border1=top|field1={{nbsp}}|bits2=16|border2=bottom|field2={{nbsp}}}}
{{APHD|8|bits1=32|border1=top|field1=Destination MAC|value1={{MACaddr|ff:ff:ff:ff:ff:ff}}|hint1=Destination MAC (DHCPREQUESTs are broadcast)}}
{{APHD|12|bits1=16|field1=EtherType|value1={{Mono|0x0800}}|hint1=0x0800 indicates IPv4|bits2=16|border2=bottom|background2=mistyrose|field2={{nbsp}}}}
{{APHD|16|bits1=0|border1=top|background1=mistyrose|field1=IPv4 packet, containing a UDP PDU with DHCP payload...}}
{{APHD|999|bits1=32|field1=Frame Check Sequence|short1=FCS}}
{{APHD|end}}
{{APHD|start|header=yew|title=IPv4 Header}}
{{APHD|0|bits1=64|field1=IPv4 header start}}
{{APHD|8|bits1=8|bits2=8|bits3=16|field1=TTL|field2=Protocol ({{Mono|17}} UDP)|field3=Header Checksum}}
{{APHD|end}}
{{APHD|start|header=no|title=UDP Header}}
{{APHD|12|bits1=32|field1=Source Address ({{IPaddr|0.0.0.0}})}}
{{APHD|16|bits1=32|field1=Destination Address ({{IPaddr|255.255.255.255}})}}
{{APHD|20|bits1=16|bits2=16|field1=Source Port (68)|field2=Destination Port (67)}}
{{APHD|24|bits1=16|bits2=16|field1=Length|field2=Checksum}}
{{APHD|end}}
{{APHD|start|header=no|title=DHCP Payload: DHCPREQUEST}}
{{APHD|28|bits1=8|bits2=8|bits3=8|bits4=8|field1=OP ({{Mono|0x01}})|hint1=BOOTREQUEST|field2=HTYPE ({{Mono|0x01}})|field3=HLEN ({{Mono|0x06}})|field4=HOPS ({{Mono|0x00}})}}
{{APHD|32|bits1=32|field1=XID ({{Mono|0x3903F326}})}}
{{APHD|36|bits1=16|bits2=16|field1=SECS ({{Mono|0x0000}})|field2=FLAGS ({{Mono|0x0000}})}}
{{APHD|40|bits1=32|field1=CIADDR (Client IP address: {{Mono|0x00000000}})}}
{{APHD|44|bits1=32|field1=YIADDR (Your IP address: {{Mono|0x00000000}})}}
{{APHD|48|bits1=32|field1=SIADDR (Server IP address: {{Mono|0xc0a80101}} or {{IPaddr|192.168.1.1}})}}
{{APHD|52|bits1=32|field1=GIADDR (Gateway IP address: {{Mono|0x00000000}})}}
{{APHD|56|bits1=128|field1=CHADDR (Client Hardware address: {{Mono|0x00053C04<br>0x8D590000<br>0x00000000<br>0x00000000}})}}
{{APHD|72|bits1=1536|field1=192 octets of 0s, or overflow space for additional options; BOOTP legacy.}}
{{APHD|264|bits1=32|field1=[[Magic Cookie]] ({{Mono|0x63825363}})}}
{{APHD|end}}
{{APHD|start|header=no|title=DHCP Options (in [[Type-length-value|TLV]] format)}}
{{APHD|268|bits1=24|background1=linen|field1=First option: {{Mono|0x350103}}: Option 53 (DHCP Message Type) 1 octet (containing DHCPREQUEST)|bits2=8|background2=linen|border2=right|field2=Second option:}}
{{APHD|272|bits1=32|background1=linen|border1=left|field1={{Mono|0x3204c0a80164}}: Option 50 (Request IP address) 4 octets (containing {{IPaddr|192.168.1.100}})|hint1=Must match YIADDR from the DHCPOFFER packet.}}
{{APHD|276|bits1=32|background1=linen|field1=Third option: {{Mono|0x3604c0a801601}}: Option: 54 (DHCP Server) 4 octets  (containing {{IPaddr|192.168.1.1}})|hint1=Server Identification: tell which offer you accept.|border1=right}}
{{APHD|280|bits1=8|background1=linen|border1=left|field1=DHCP Server cont...|bits2=1|field2=<small>{{Mono|ff}}</small>|hint2=0xff Option end mark}}
{{APHD|end}}