error (broken trust chain) resolving

[Brian J. Murrell]

Since enabling DNSSEC on my resolving server I have been seeing various 
instances of the following sort of messages:

named error (broken trust chain) resolving '133.168.163.66.sa-
trusted.bondedsender.org/TXT/IN': 173.45.100.146#53
named error (broken trust chain) resolving 
'173.65.147.69.bb.barracudacentral.org/A/IN': 75.101.148.228#53
named error (broken trust chain) resolving '133.168.163.66.sa-
accredit.habeas.com/TXT/IN': 72.232.184.122#53
named error (broken trust chain) resolving 
'151.168.163.66.bb.barracudacentral.org/A/IN': 75.101.148.228#53
named error (broken trust chain) resolving 
'149.65.147.69.bb.barracudacentral.org/A/IN': 75.101.143.130#53
named error (broken trust chain) resolving 
'133.168.163.66.bb.barracudacentral.org/A/IN': 75.101.130.80#53
named error (broken trust chain) resolving 
'52.241.193.67.bb.barracudacentral.org/A/IN': 75.101.143.130#53
named error (broken trust chain) resolving 
'61.94.196.66.bb.barracudacentral.org/A/IN': 75.101.148.228#53
named error (broken trust chain) resolving 
'154.168.163.66.bb.barracudacentral.org/A/IN': 75.101.130.80#53
named error (broken trust chain) resolving 
'106.94.196.66.bb.barracudacentral.org/A/IN': 75.101.130.80#53
named error (broken trust chain) resolving 
'184.34.137.98.bb.barracudacentral.org/A/IN': 75.101.143.130#53
named error (broken trust chain) resolving 
'92.45.136.98.bb.barracudacentral.org/A/IN': 75.101.148.228#53
named error (broken trust chain) resolving 
'36.34.137.98.bb.barracudacentral.org/A/IN': 75.101.130.80#53
named error (broken trust chain) resolving 
'154.168.163.66.bb.barracudacentral.org/A/IN': 75.101.143.130#53
named error (broken trust chain) resolving 
'64.218.193.67.bb.barracudacentral.org/A/IN': 75.101.148.228#53
named error (broken trust chain) resolving '92.45.136.98.sa-
accredit.habeas.com/TXT/IN': 173.45.100.162#53
named error (broken trust chain) resolving 
'148.65.147.69.bb.barracudacentral.org/A/IN': 75.101.130.80#53
named error (broken trust chain) resolving 
'158.169.163.66.bb.barracudacentral.org/A/IN': 75.101.143.130#53
named error (broken trust chain) resolving 
'172.65.147.69.bb.barracudacentral.org/A/IN': 75.101.148.228#53
named error (broken trust chain) resolving 
'45.34.137.98.bb.barracudacentral.org/A/IN': 75.101.148.228#53
named error (broken trust chain) resolving '92.45.136.98.sa-
trusted.bondedsender.org/TXT/IN': 64.251.27.187#53
named error (broken trust chain) resolving 
'40.34.137.98.bb.barracudacentral.org/A/IN': 75.101.148.228#53
named error (broken trust chain) resolving '101.43.195.217.sa-
accredit.habeas.com/TXT/IN': 64.251.27.185#53
named error (broken trust chain) resolving 
'103.179.83.130.bb.barracudacentral.org/A/IN': 75.101.143.130#53
named error (broken trust chain) resolving 
'101.43.195.217.bb.barracudacentral.org/A/IN': 75.101.143.130#53
named error (broken trust chain) resolving '101.43.195.217.sa-
trusted.bondedsender.org/TXT/IN': 72.232.192.162#53

I haven't been able to find an explanation of what that "broken trust chain" 
message means, exactly.

Anyone care to explain?

Thanx,
b.