WordPress – Why do HTTP loopback connections not work on the subdomains

I have a shared hosting account at Jumba running Linux kernel 2.6.9-103.ELsmp (don't know if that helps) with cpanel 1.0 (RC1).

I am using the WordPress plugin Backup Buddy, which requires HTTP loopback connections to monitor / complete backups. This works fine on memelab.com.au, but doesn't work at any subdomain (e.g.: staging.memelab.com.au).

Is it possible to setup an A record or some such to remedy this?

I'm aware of a workaround, (setting WP_ALTERNATE_CRON) but I find this unsatisfactory due to the messy URLs.

BackupBuddy:_Frequent_Support_Issues#HTTP_Loopback_Connections_Disabled

Here is the reply from my host:

…as main
domain have it's own separate DNS entry it have localhost entry which
helps for looback connections where as subdomains don't have separate
DNS zone, so it is not possible to create looback connections for it.

I have cpanel access to the 'advanced zone editor' – is there anything tricky I can do there? maybe 127.0.0.2? (I remember reading that there were at least 8 available local IPs available on (some) Linuxes.)

All the A records point to the server IP, with the exception of localhost.memelab.com.au which points to 127.0.0.1.

I've just tried entering a new A record: localhost.itours.memelab.com.au pointing to 127.0.0.2. I still get the warning in Backup Buddy that loopback is not active, and Cpanel won't let me enter 127.0.0.1 (guess it doesn't work like that!)

nslookup itours.memelab.com.au
Server:     203.88.112.33
Address:    203.88.112.33#53

Non-authoritative answer:
Name:   itours.memelab.com.au
Address: 117.55.224.177