Few things I have learnt on my Autodeploy journey regarding DHCP…
When using DHCP, use reservations, then add Option 12 to your reservation and enter the host name. When your host gets added to vCenter it will come in with proper host name and qualified with domain (depending on other setups).
Also on properties of your reservation (using W2008R2), select DNS tab, and allow updates by ensuring Enable DNS dynamic updates is ticked, then selecting option Always dynamically update DNS A and PTR records. I Also tick box Dynamically update DNS A and PTR records for DHCP clients that do not request updates. This will mean you will get your auto-deploy hosted added to DNS with Host(A) record (and if you have remembered to create a reverse lookup zone for your subnet)a PTR record as well. This saves the work of adding this manually.
And finally… setting Spanning-Tree PortFast on your switch port with which your host is booting and getting DHCP lease is required. Have seen 2nd-stage DHCP request within gPXE failing / timeout unless Spanning-Tree PortFast is set.