constant flow of root queries

["Brian Collins" <listbc () newnanutilities org>]

Good day folks.  This morning an admin asked us to check on a large amount
of traffic targeting several DNS servers in our network (both our own DNS
servers and customer co-located DNS servers).  In looking at the traffic I
see that the source is making several queries a second for DNS root.  I have
included a small sample from tcpdump below.  Not sure what the motive is
here.  The TTLs are all 235.  The random source ports makes me think
possibly spoofed traffic.  I can put packet dumps up on a website in libpcap
format if anyone is interested.  They are still going on as I type this.

Thanks for any insight you can lend.


08:44:31.681706 IP 207.210.68.202.18257 > 216.130.152.71.53:  7127+ [1au]
ANY ANY? . (28)
08:44:31.935719 IP 207.210.68.202.17460 > 216.130.152.71.53:  16133+ [1au]
ANY ANY? . (28)
08:44:32.191226 IP 207.210.68.202.11958 > 216.130.152.71.53:  24095+ [1au]
ANY ANY? . (28)
08:44:32.453721 IP 207.210.68.202.30962 > 216.130.152.71.53:  28728+ [1au]
ANY ANY? . (28)
08:44:32.965355 IP 207.210.68.202.30683 > 216.130.152.71.53:  12271+ [1au]
ANY ANY? . (28)
08:44:33.468862 IP 207.210.68.202.9966 > 216.130.152.71.53:  28170+ [1au]
ANY ANY? . (28)
08:44:33.720408 IP 207.210.68.202.9920 > 216.130.152.71.53:  28160+ [1au]
ANY ANY? . (28)
08:44:33.976693 IP 207.210.68.202.22511 > 216.130.152.71.53:  9346+ [1au]
ANY ANY? . (28)
08:44:34.233664 IP 207.210.68.202.20625 > 216.130.152.71.53:  18580+ [1au]
ANY ANY? . (28)
08:44:34.495015 IP 207.210.68.202.7023 > 216.130.152.71.53:  7968+ [1au] ANY
ANY? . (28)
08:44:34.742492 IP 207.210.68.202.6257 > 216.130.152.71.53:  11859+ [1au]
ANY ANY? . (28)
08:44:35.001415 IP 207.210.68.202.25244 > 216.130.152.71.53:  5372+ [1au]
ANY ANY? . (28)
08:44:35.257812 IP 207.210.68.202.17576 > 216.130.152.71.53:  14270+ [1au]
ANY ANY? . (28)
08:44:35.778259 IP 207.210.68.202.3384 > 216.130.152.71.53:  1508+ [1au] ANY
ANY? . (28)
08:44:36.034492 IP 207.210.68.202.13754 > 216.130.152.71.53:  23670+ [1au]
ANY ANY? . (28)
08:44:36.290463 IP 207.210.68.202.11008 > 216.130.152.71.53:  8899+ [1au]
ANY ANY? . (28)
08:44:36.805271 IP 207.210.68.202.18348 > 216.130.152.71.53:  19806+ [1au]
ANY ANY? . (28)
08:44:37.061876 IP 207.210.68.202.19532 > 216.130.152.71.53:  31844+ [1au]
ANY ANY? . (28)