diff --git a/hosts b/hosts
index bd6efba..7e55bd0 100644
--- a/hosts
+++ b/hosts
@@ -1,4 +1,4 @@
-[servers]
+# Group names should not contain any special characters except for underscores _, hyphens -, and periods ..
 
 [proxmox]
 mox1            ansible_host=mox1.verdnatura.es
@@ -56,7 +56,7 @@ ve5             ansible_host=ve5.verdnatura.es
 vcenter         ansible_host=vcenter.verdnatura.es
 
 
-[pro-linux]
+[pro_linux]
 
 db              ansible_host=db.static.verdnatura.es
 pbx             ansible_host=pbx.static.verdnatura.es
@@ -94,7 +94,7 @@ integra2        ansible_host=integra2.static.verdnatura.es
 goat            ansible_host=goat.static.verdnatura.es
 test801         ansible_host=test801.static.verdnatura.es
 
-[pro-windows]
+[pro_windows]
 adwindows       ansible_host=adwindows.static.verdnatura.es
 franceexpress   ansible_host=franceexpress.static.verdnatura.es
 logiflora       ansible_host=logiflora.static.verdnatura.es