unexpected log entries

["Paolo Mattiangeli" <pamatt () centrodiascolto it>]

Hi everybody, I guess maybe someone out there can help me with this. I have
a w2k server running IIS 5 and keep receiving what I think to be "probes" on
my web server. Today I found in the log the following entry:

2002-12-07 14:33:32 200.170.226.83 - 192.168.100.7 80 GET /default.ida
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN%u90
90%u6858%ucbd3%u7801%u9090%u6858%ucbd3%u7801%u9090%u6858%ucbd3%u7801%u9090%u
9090%u8190%u00c3%u0003%u8b00%u531b%u53ff%u0078%u0000%u00=a 200 -

which I guess to be a tentative of buffer overrun on my web server. I have
some difficulties to understand what is the matter here, but the thing that
most worries me is the final "200 - " which in some way could mean that the
response of the server is positive (in most cases it ist 404 - or 500 -).
Could someone help?

Thanks and regards

pamatt