Yes, it is.
I just tried it out.
Here's the part out of my mirror.log. Maybe it helps.
14:24:18 vrb/sys Computer Ip Addr: 192.168.1.3
14:24:18 min/gen scr: mirror begin...
14:24:18 vrb/gen Operation set to INST_OP_MIRROR_DOALL
14:24:18 nrm/int SYNCER: Proxy 192.168.1.2:3128
14:24:18 nrm/int SYNCER: Type: standard HTTP proxy (rfc2616,2617)
14:24:18 nrm/int SYNCER: Auth: no authentication
14:24:18 min/gen GUID: 2ea18fb4-38db-4d00-a1ff-3a31535759e1
14:24:18 nrm/gen scr: Mirroring...
14:24:18 nrm/gen Server definition(s) loaded for 'main': 32 (maintenance:0)
14:24:18 nrm/gen SelectCurrent: selected server 'Download5 AVAST server' from 'main'
14:24:18 nrm/gen scr: Using server:
http://download5.avast.com/iavs4x14:24:18 nrm/gen Server definition(s) loaded for 'main': 32 (maintenance:0)
14:24:18 nrm/gen SelectCurrent: selected server 'Download23 AVAST server' from 'main'
14:24:18 nrm/gen scr: Using server:
http://download23.avast.com/iavs4x14:24:22 nrm/gen scr: Setting product 'av_mgm' files (94 of 996 set)
14:24:23 nrm/gen scr: Resetting existing files (reset 94 files, leaving 0 files).
14:24:23 nrm/gen Server definition(s) loaded for 'main': 32 (maintenance:0)
14:24:23 nrm/gen SelectCurrent: selected server 'Download14 AVAST server' from 'main'
14:24:23 nrm/gen scr: Using server:
http://download14.avast.com/iavs4x14:24:23 nrm/gen scr: mirroring 'av_mgm' - nothing to do.
14:24:23 nrm/gen scr: Setting product 'av_net' files (684 of 996 set)
14:24:26 nrm/gen scr: Resetting existing files (reset 586 files, leaving 98 files).
14:24:26 nrm/gen Server definition(s) loaded for 'main': 32 (maintenance:0)
14:24:26 nrm/gen SelectCurrent: selected server 'Download27 AVAST server' from 'main'
14:24:26 nrm/gen scr: Using server:
http://download27.avast.com/iavs4x14:24:26 min/gen scr: mirroring 'av_net'.
14:24:26 nrm/gen InvalidateCurrent: invalidated server 'Download27 AVAST server' from 'main'
14:24:26 nrm/gen SelectCurrent: selected server 'Download3 AVAST server' from 'main'
14:24:26 nrm/gen scr: Using server:
http://download3.avast.com/iavs4x14:24:26 dbg/int while trying to get file 'setif_av_net-ad-ab.vpu', error 0x20000006 has occured, try 1
.
.
.
.
14:25:29 nrm/gen InvalidateCurrent: invalidated server 'Download20 AVAST server' from 'main'
14:25:29 min/gen SelectCurrent: unable to find any suitable server in 'main'
14:25:29 dbg/int while trying to get file 'setif_av_net-ad-ab.vpu', error 0x20000006 has occured, try 32
14:25:29 min/int tried 32 servers to get file 'setif_av_net-ad-ab.vpu', but failed (0x20000006)
14:25:29 min/gen scr: downloading of file 'setif_av_net-ad-ab.vpu' failed.
14:25:29 min/gen Err:Other HTTP error (403), while trying 66.98.136.92:3128/http://download20.avast.com/iavs4x/setif_av_net-ad-ab.vpu
14:25:29 min/gen Return code: 0x20000006 [Other HTTP error (403), while trying 66.98.136.92:3128/http://download20.avast.com/iavs4x/setif_av_net-ad-ab.vpu]
14:25:29 min/gen Stopped: 21.11.2005, 14:25:29
What does this mean?? -> 66.98.136.92:3128