Next Step: Ping scan

nmap -sP -PS22,25,53,80,113,31338 -PA80,113,21000 -PU53,19000 -PE -PM -g 53 -oA foocorp-ps [foocorpnetblocks]
[ ... ]
Host bigip-chi.foocorp.com (200.247.228.130) appears to be up.
Host bigip1-chi.foocorp.com (200.247.228.131) appears to be up.
Host bigip2-chi.foocorp.com (200.247.228.132) appears to be up.
Host threed-chi.foocorpcommerce.com (200.247.228.133) appears to be up.
Host ns1-chi.foocorp.com (200.247.228.135) appears to be up.
Host dev-chi.foocorpcommerce.com (200.247.228.137) appears to be up.
Host devdb-chi.foocorpcommerce.com (200.247.228.138) appears to be up.
Host staging-chi.foocorpcommerce.com (200.247.228.140) appears to be up.
Host STAGING2.FOOCORP.COM (200.247.228.141) appears to be up.
[ ... ]
Nmap run completed -- 4397 IP addresses (950 hosts up) scanned in 752.776 seconds