A minute's detective work, or less, shows that the problem
starts at mae-west.net99.net -- or more precisely, between
MCI's FIX-West-NAP and mae-west.

Traceroute from Stanford to netbsd.warped.com
 1  jenkins-gateway.Stanford.EDU (36.102.0.1)  3.162 ms  2.942 ms  3.048 ms
 2  SUNet-Gateway.Stanford.EDU (36.1.0.201)  3.614 ms  3.382 ms  3.915 ms
 3  198.31.10.2 (198.31.10.2)  3.708 ms  3.673 ms  3.45 ms
 4  192.31.48.2 (192.31.48.2)  56.426 ms  224.663 ms  22.295 ms
 5  cpe1-fddi-0.hay.mci.net (192.31.48.245)  3.971 ms  4.079 ms  4.182 ms
 6  borderx1-hssi2-0.SanFrancisco.mci.net (204.70.158.101)  5.678 ms  5.722 ms  5.625 ms
 7  core2-fddi-0.SanFrancisco.mci.net (204.70.158.49)  6.377 ms  6.302 ms  6.172 ms
 8  borderx2-fddi-1.SanFrancisco.mci.net (204.70.158.68)  5.832 ms  6.085 ms  6.071 ms
 9  fix-west-nap.SanFrancisco.mci.net (204.70.158.118)  7.771 ms  7.249 ms  6.998 ms
10  mae-west.net99.net (198.32.136.16)  25.593 ms  24.515 ms  27.958 ms
11  mae-west.best.net (198.32.136.36)  28.375 ms  21.332 ms  18.075 ms
12  netbsd.warped.com (205.149.163.23)  14.169 ms  14.666 ms  15.205 ms

ping -p 00000000fffffffff fix-west-nap.sanfrancisco.mci.net:
(Hey, wasn't the west-coast FIX at Moffet Field??)

PATTERN: 0x00000000ffffffff0f
PING fix-west-nap.sanfrancisco.mci.net (204.70.158.118): 56 data bytes
64 bytes from 204.70.158.118: icmp_seq=0 ttl=247 time=8.1 ms
64 bytes from 204.70.158.118: icmp_seq=1 ttl=247 time=7.6 ms
64 bytes from 204.70.158.118: icmp_seq=2 ttl=247 time=8.1 ms
64 bytes from 204.70.158.118: icmp_seq=3 ttl=247 time=7.8 ms
64 bytes from 204.70.158.118: icmp_seq=4 ttl=247 time=7.9 ms
64 bytes from 204.70.158.118: icmp_seq=5 ttl=247 time=7.5 ms

--- fix-west-nap.sanfrancisco.mci.net ping statistics ---
6 packets transmitted, 6 packets received, 0% packet loss
round-trip min/avg/max = 7.5/7.8/8.1 ms

ping -p 00000000fffffffff mae-west.net99.net
PATTERN: 0x00000000ffffffff
PING mae-west.net99.net (198.32.136.16): 56 data bytes
64 bytes from 198.32.136.16: icmp_seq=0 ttl=246 time=13.4 ms
wrong data byte #24 should be 0x0 but was 0xff
	33 ab e4 30 a7 82 e 0 0 0 0 0 ff ff ff ff 0 0 0 0 ff ff ff ff ff ff ff ff ff ff ff ff 
	0 0 0 0 ff ff ff ff ff ff ff ff ff ff ff ff 
64 bytes from 198.32.136.16: icmp_seq=1 ttl=246 time=14.8 ms
wrong data byte #24 should be 0x0 but was 0xff
	34 ab e4 30 a7 66 e 0 0 0 0 0 ff ff ff ff 0 0 0 0 ff ff ff ff ff ff ff ff ff ff ff ff 
	0 0 0 0 ff ff ff ff ff ff ff ff ff ff ff ff 
64 bytes from 198.32.136.16: icmp_seq=2 ttl=246 time=22.3 ms
wrong data byte #24 should be 0x0 but was 0xff
	35 ab e4 30 a7 66 e 0 0 0 0 0 ff ff ff ff 0 0 0 0 ff ff ff ff ff ff ff ff ff ff ff ff 
	0 0 0 0 ff ff ff ff ff ff ff ff ff ff ff ff 
64 bytes from 198.32.136.16: icmp_seq=3 ttl=246 time=14.8 ms
wrong data byte #24 should be 0x0 but was 0xff
	36 ab e4 30 e5 64 e 0 0 0 0 0 ff ff ff ff 0 0 0 0 ff ff ff ff ff ff ff ff ff ff ff ff 
	0 0 0 0 ff ff ff ff ff ff ff ff ff ff ff ff 
64 bytes from 198.32.136.16: icmp_seq=4 ttl=246 time=15.9 ms
wrong data byte #24 should be 0x0 but was 0xff
	37 ab e4 30 a5 66 e 0 0 0 0 0 ff ff ff ff 0 0 0 0 ff ff ff ff ff ff ff ff ff ff ff ff 
	0 0 0 0 ff ff ff ff ff ff ff ff ff ff ff ff 
64 bytes from 198.32.136.16: icmp_seq=5 ttl=246 time=14.4 ms
wrong data byte #24 should be 0x0 but was 0xff
	38 ab e4 30 a7 66 e 0 0 0 0 0 ff ff ff ff 0 0 0 0 ff ff ff ff ff ff ff ff ff ff ff ff 
	0 0 0 0 ff ff ff ff ff ff ff ff ff ff ff ff 
64 bytes from 198.32.136.16: icmp_seq=6 ttl=246 time=12.0 ms
wrong data byte #24 should be 0x0 but was 0xff
	39 ab e4 30 a6 66 e 0 0 0 0 0 ff ff ff ff 0 0 0 0 ff ff ff ff ff ff ff ff ff ff ff ff 
	0 0 0 0 ff ff ff ff ff ff ff ff ff ff ff ff 
64 bytes from 198.32.136.16: icmp_seq=7 ttl=246 time=12.1 ms
wrong data byte #24 should be 0x0 but was 0xff
	3a ab e4 30 a5 66 e 0 0 0 0 0 ff ff ff ff 0 0 0 0 ff ff ff ff ff ff ff ff ff ff ff ff 
	0 0 0 0 ff ff ff ff ff ff ff ff ff ff ff ff 

--- mae-west.net99.net ping statistics ---
8 packets transmitted, 8 packets received, 0% packet loss
round-trip min/avg/max = 12.0/14.9/22.3 ms