dig +trace problems

[Will Yardley]

Why does dig +trace fail on this:
jazz% dig +trace ilove.lancaster.pa.us. 

; <<>> DiG 9.3.0s20020703 <<>> +trace ilove.lancaster.pa.us.
;; global options:  printcmd
.                       112110  IN      NS      G.ROOT-SERVERS.NET.
.                       112110  IN      NS      H.ROOT-SERVERS.NET.
.                       112110  IN      NS      I.ROOT-SERVERS.NET.
.                       112110  IN      NS      J.ROOT-SERVERS.NET.
.                       112110  IN      NS      K.ROOT-SERVERS.NET.
.                       112110  IN      NS      L.ROOT-SERVERS.NET.
.                       112110  IN      NS      M.ROOT-SERVERS.NET.
.                       112110  IN      NS      A.ROOT-SERVERS.NET.
.                       112110  IN      NS      B.ROOT-SERVERS.NET.
.                       112110  IN      NS      C.ROOT-SERVERS.NET.
.                       112110  IN      NS      D.ROOT-SERVERS.NET.
.                       112110  IN      NS      E.ROOT-SERVERS.NET.
.                       112110  IN      NS      F.ROOT-SERVERS.NET.
;; Received 308 bytes from 127.0.0.1#53(127.0.0.1) in 7 ms

us.                     172800  IN      NS      A.GTLD.BIZ.
us.                     172800  IN      NS      B.GTLD.BIZ.
us.                     172800  IN      NS      C.GTLD.BIZ.
;; Received 143 bytes from 192.112.36.4#53(G.ROOT-SERVERS.NET) in 272 ms

dig: couldn't get address for 'B.GTLD.BIZ': not found

I can still get a response from C.GTLD.BIZ. - why does it fail on not
being able to find the address for b.gtld.biz? shouldn't it ask
c.gtld.biz and continue?

As an aside, these are the servers that are supposedly authoritative for
gtld.biz.:

;; ADDITIONAL SECTION:
NS1.NEULEVEL.biz.       7200    IN      A       209.173.53.74
NS2.NEULEVEL.biz.       7200    IN      A       209.173.57.74
NS3.NEULEVEL.biz.       7200    IN      A       209.173.53.84
NS4.NEULEVEL.biz.       7200    IN      A       66.129.74.199

however, at least one of these servers doesn't seem to have a glue
record for b.gtld.biz:

jazz% dig b.gtld.biz. @66.129.74.199

; <<>> DiG 9.3.0s20020703 <<>> b.gtld.biz. @66.129.74.199
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 31453
;; flags: qr aa rd; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;b.gtld.biz.                    IN      A

;; AUTHORITY SECTION:
gtld.biz.               1800    IN      SOA     ns1.neulevel.biz.
sec_grp.neustar.com. 1026699675 10800 3600 1209600 43200

-- 
No copies, please.
To reply privately, simply reply; don't remove anything.