[vadblm]

Под лупбэк выделена целая подсеть:

Код:

NetRange:       127.0.0.0 - 127.255.255.255
CIDR:           127.0.0.0/8
OriginAS:       
NetName:        SPECIAL-IPV4-LOOPBACK-IANA-RESERVED
NetHandle:      NET-127-0-0-0-1
Parent:         
NetType:        IANA Special Use
Comment:        This block is assigned for use as the Internet
Comment:        host loopback address. Datagrams sent to
Comment:        addresses anywhere within this block loops back 
Comment:        inside the host. Many implementation only
Comment:        support this for 127.0.0.1. This block was 
Comment:        assigned by the IETF in the Standard document, 
Comment:        RFC 1122 and is further documented in the Best
Comment:        Current Practice document RFC 5735. These
Comment:        documents can be found at:
Comment:        http://www.rfc-editor.org/rfc/rfc1122.txt
Comment:        http://www.rfc-editor.org/rfc/rfc5735.txt
RegDate:        

Updated:        2010-04-14
Ref:            http://whois.arin.net/rest/net/NET-127-0-0-0-1

127.0.1.1 и 127.0.0.1 равнозначны, просто дебианщики (и с ними убунтовцы) решили так выпендриться.

ЗЫ. А вот к примеру в NTP к локальным часам следует обращаться по адресу 127.127.1.0 и никак иначе. Всё это просто условности.