Hi Nicolas,
Please look at the following link this should help you achieve your desired result.
http://www.cisco.com/en/US/docs/app_ntwk_services/data_center_app_services/css11000series/v5.00/configuration/advanced/guide/HTTPHead.html
Something like below:
header-field-group A
header-field ual host contains "domain1"
header-field-group B
header-field ual host contains "domain2"
header-field-group C
header-field ual host contains "domain3"
! ********************** OWNER ***************************
owner arrowpoint
content ruleA
protocol tcp
vip address 192.168.128.151
port 80
url "/*"
add service server1
add service server2
content ruleA1
protocol tcp
vip address 192.168.128.151
port 80
url "/*"
header-field-rule A
add service server11
add service server12
content ruleA2
protocol tcp
vip address 192.168.128.151
port 80
url "/*"
header-field-rule B
add service server21
add service server22
content ruleA3
protocol tcp
vip address 192.168.128.151
port 80
url "/*"
header-field-rule C
add service server31
add service server32
Hope that helps.
regards,
Ajay Kumar