[0] 0.46.122.168.in-addr.arpa.: domain name does not exist [3600] 1.46.122.168.in-addr.arpa. domain name pointer comm595-0302net-gw.bu.edu [0] 2.46.122.168.in-addr.arpa.: domain name does not exist [0] 3.46.122.168.in-addr.arpa.: domain name does not exist [0] 4.46.122.168.in-addr.arpa.: domain name does not exist [0] 5.46.122.168.in-addr.arpa.: domain name does not exist [0] 6.46.122.168.in-addr.arpa.: domain name does not exist [0] 7.46.122.168.in-addr.arpa.: domain name does not exist [0] 8.46.122.168.in-addr.arpa.: domain name does not exist [0] 9.46.122.168.in-addr.arpa.: domain name does not exist [0] 10.46.122.168.in-addr.arpa.: domain name does not exist [3600] 11.46.122.168.in-addr.arpa. domain name pointer comm595-302aer01.bu.edu [3600] 12.46.122.168.in-addr.arpa. domain name pointer comm595-315aer01.bu.edu [3600] 13.46.122.168.in-addr.arpa. domain name pointer comm595-322aer01.bu.edu [0] 14.46.122.168.in-addr.arpa.: domain name does not exist [0] 15.46.122.168.in-addr.arpa.: domain name does not exist [0] 16.46.122.168.in-addr.arpa.: domain name does not exist [0] 17.46.122.168.in-addr.arpa.: domain name does not exist [0] 18.46.122.168.in-addr.arpa.: domain name does not exist [0] 19.46.122.168.in-addr.arpa.: domain name does not exist [0] 20.46.122.168.in-addr.arpa.: domain name does not exist [0] 21.46.122.168.in-addr.arpa.: domain name does not exist [0] 22.46.122.168.in-addr.arpa.: domain name does not exist [0] 23.46.122.168.in-addr.arpa.: domain name does not exist [0] 24.46.122.168.in-addr.arpa.: domain name does not exist [0] 25.46.122.168.in-addr.arpa.: domain name does not exist [0] 26.46.122.168.in-addr.arpa.: domain name does not exist [0] 27.46.122.168.in-addr.arpa.: domain name does not exist [0] 28.46.122.168.in-addr.arpa.: domain name does not exist [0] 29.46.122.168.in-addr.arpa.: domain name does not exist [0] 30.46.122.168.in-addr.arpa.: domain name does not exist [3600] 31.46.122.168.in-addr.arpa. domain name pointer comm595-0302-031.bu.edu [3600] 32.46.122.168.in-addr.arpa. domain name pointer comm595-0302-032.bu.edu [3600] 33.46.122.168.in-addr.arpa. domain name pointer comm595-0302-033.bu.edu [3600] 34.46.122.168.in-addr.arpa. domain name pointer comm595-0302-034.bu.edu [3600] 35.46.122.168.in-addr.arpa. domain name pointer comm595-0302-035.bu.edu [3600] 36.46.122.168.in-addr.arpa. domain name pointer comm595-0302-036.bu.edu [3600] 37.46.122.168.in-addr.arpa. domain name pointer comm595-0302-037.bu.edu [3600] 38.46.122.168.in-addr.arpa. domain name pointer comm595-0302-038.bu.edu [3600] 39.46.122.168.in-addr.arpa. domain name pointer comm595-0302-039.bu.edu [3600] 40.46.122.168.in-addr.arpa. domain name pointer comm595-0302-040.bu.edu [3600] 41.46.122.168.in-addr.arpa. domain name pointer comm595-0302-041.bu.edu [3600] 42.46.122.168.in-addr.arpa. domain name pointer comm595-0302-042.bu.edu [3600] 43.46.122.168.in-addr.arpa. domain name pointer comm595-0302-043.bu.edu [3600] 44.46.122.168.in-addr.arpa. domain name pointer comm595-0302-044.bu.edu [3600] 45.46.122.168.in-addr.arpa. domain name pointer comm595-0302-045.bu.edu [3600] 46.46.122.168.in-addr.arpa. domain name pointer comm595-0302-046.bu.edu [3600] 47.46.122.168.in-addr.arpa. domain name pointer comm595-0302-047.bu.edu [3600] 48.46.122.168.in-addr.arpa. domain name pointer comm595-0302-048.bu.edu [3600] 49.46.122.168.in-addr.arpa. domain name pointer comm595-0302-049.bu.edu [3600] 50.46.122.168.in-addr.arpa. domain name pointer comm595-0302-050.bu.edu [3600] 51.46.122.168.in-addr.arpa. domain name pointer comm595-0302-051.bu.edu [3600] 52.46.122.168.in-addr.arpa. domain name pointer comm595-0302-052.bu.edu [3600] 53.46.122.168.in-addr.arpa. domain name pointer comm595-0302-053.bu.edu [3600] 54.46.122.168.in-addr.arpa. domain name pointer comm595-0302-054.bu.edu [3600] 55.46.122.168.in-addr.arpa. domain name pointer comm595-0302-055.bu.edu [3600] 56.46.122.168.in-addr.arpa. domain name pointer comm595-0302-056.bu.edu [3600] 57.46.122.168.in-addr.arpa. domain name pointer comm595-0302-057.bu.edu [3600] 58.46.122.168.in-addr.arpa. domain name pointer comm595-0302-058.bu.edu [3600] 59.46.122.168.in-addr.arpa. domain name pointer comm595-0302-059.bu.edu [3600] 60.46.122.168.in-addr.arpa. domain name pointer comm595-0302-060.bu.edu [3600] 61.46.122.168.in-addr.arpa. domain name pointer comm595-0302-061.bu.edu [3600] 62.46.122.168.in-addr.arpa. domain name pointer comm595-0302-062.bu.edu [3600] 63.46.122.168.in-addr.arpa. domain name pointer comm595-0302-063.bu.edu [3600] 64.46.122.168.in-addr.arpa. domain name pointer comm595-0302-064.bu.edu [3600] 65.46.122.168.in-addr.arpa. domain name pointer comm595-0302-065.bu.edu [3600] 66.46.122.168.in-addr.arpa. domain name pointer comm595-0302-066.bu.edu [3600] 67.46.122.168.in-addr.arpa. domain name pointer comm595-0302-067.bu.edu [3600] 68.46.122.168.in-addr.arpa. domain name pointer comm595-0302-068.bu.edu [3600] 69.46.122.168.in-addr.arpa. domain name pointer comm595-0302-069.bu.edu [3600] 70.46.122.168.in-addr.arpa. domain name pointer comm595-0302-070.bu.edu [3600] 71.46.122.168.in-addr.arpa. domain name pointer comm595-0302-071.bu.edu [3600] 72.46.122.168.in-addr.arpa. domain name pointer comm595-0302-072.bu.edu [3600] 73.46.122.168.in-addr.arpa. domain name pointer comm595-0302-073.bu.edu [3600] 74.46.122.168.in-addr.arpa. domain name pointer comm595-0302-074.bu.edu [3600] 75.46.122.168.in-addr.arpa. domain name pointer comm595-0302-075.bu.edu [3600] 76.46.122.168.in-addr.arpa. domain name pointer comm595-0302-076.bu.edu [3600] 77.46.122.168.in-addr.arpa. domain name pointer comm595-0302-077.bu.edu [3600] 78.46.122.168.in-addr.arpa. domain name pointer comm595-0302-078.bu.edu [3600] 79.46.122.168.in-addr.arpa. domain name pointer comm595-0302-079.bu.edu [3600] 80.46.122.168.in-addr.arpa. domain name pointer comm595-0302-080.bu.edu [3600] 81.46.122.168.in-addr.arpa. domain name pointer comm595-0302-081.bu.edu [3600] 82.46.122.168.in-addr.arpa. domain name pointer comm595-0302-082.bu.edu [3600] 83.46.122.168.in-addr.arpa. domain name pointer comm595-0302-083.bu.edu [3600] 84.46.122.168.in-addr.arpa. domain name pointer comm595-0302-084.bu.edu [3600] 85.46.122.168.in-addr.arpa. domain name pointer comm595-0302-085.bu.edu [3600] 86.46.122.168.in-addr.arpa. domain name pointer comm595-0302-086.bu.edu [3600] 87.46.122.168.in-addr.arpa. domain name pointer comm595-0302-087.bu.edu [3600] 88.46.122.168.in-addr.arpa. domain name pointer comm595-0302-088.bu.edu [3600] 89.46.122.168.in-addr.arpa. domain name pointer comm595-0302-089.bu.edu [3600] 90.46.122.168.in-addr.arpa. domain name pointer comm595-0302-090.bu.edu [3600] 91.46.122.168.in-addr.arpa. domain name pointer comm595-0302-091.bu.edu [3600] 92.46.122.168.in-addr.arpa. domain name pointer comm595-0302-092.bu.edu [3600] 93.46.122.168.in-addr.arpa. domain name pointer comm595-0302-093.bu.edu [3600] 94.46.122.168.in-addr.arpa. domain name pointer comm595-0302-094.bu.edu [3600] 95.46.122.168.in-addr.arpa. domain name pointer comm595-0302-095.bu.edu [3600] 96.46.122.168.in-addr.arpa. domain name pointer comm595-0302-096.bu.edu [3600] 97.46.122.168.in-addr.arpa. domain name pointer comm595-0302-097.bu.edu [3600] 98.46.122.168.in-addr.arpa. domain name pointer comm595-0302-098.bu.edu [3600] 99.46.122.168.in-addr.arpa. domain name pointer comm595-0302-099.bu.edu [3600] 100.46.122.168.in-addr.arpa. domain name pointer comm595-0302-100.bu.edu [3600] 101.46.122.168.in-addr.arpa. domain name pointer comm595-0302-101.bu.edu [3600] 102.46.122.168.in-addr.arpa. domain name pointer comm595-0302-102.bu.edu [3600] 103.46.122.168.in-addr.arpa. domain name pointer comm595-0302-103.bu.edu [3600] 104.46.122.168.in-addr.arpa. domain name pointer comm595-0302-104.bu.edu [3600] 105.46.122.168.in-addr.arpa. domain name pointer comm595-0302-105.bu.edu [3600] 106.46.122.168.in-addr.arpa. domain name pointer comm595-0302-106.bu.edu [3600] 107.46.122.168.in-addr.arpa. domain name pointer comm595-0302-107.bu.edu [3600] 108.46.122.168.in-addr.arpa. domain name pointer comm595-0302-108.bu.edu [3600] 109.46.122.168.in-addr.arpa. domain name pointer comm595-0302-109.bu.edu [3600] 110.46.122.168.in-addr.arpa. domain name pointer comm595-0302-110.bu.edu [3600] 111.46.122.168.in-addr.arpa. domain name pointer comm595-0302-111.bu.edu [3600] 112.46.122.168.in-addr.arpa. domain name pointer comm595-0302-112.bu.edu [3600] 113.46.122.168.in-addr.arpa. domain name pointer comm595-0302-113.bu.edu [3600] 114.46.122.168.in-addr.arpa. domain name pointer comm595-0302-114.bu.edu [3600] 115.46.122.168.in-addr.arpa. domain name pointer comm595-0302-115.bu.edu [3600] 116.46.122.168.in-addr.arpa. domain name pointer comm595-0302-116.bu.edu [3600] 117.46.122.168.in-addr.arpa. domain name pointer comm595-0302-117.bu.edu [3600] 118.46.122.168.in-addr.arpa. domain name pointer comm595-0302-118.bu.edu [3600] 119.46.122.168.in-addr.arpa. domain name pointer comm595-0302-119.bu.edu [3600] 120.46.122.168.in-addr.arpa. domain name pointer comm595-0302-120.bu.edu [3600] 121.46.122.168.in-addr.arpa. domain name pointer comm595-0302-121.bu.edu [3600] 122.46.122.168.in-addr.arpa. domain name pointer comm595-0302-122.bu.edu [3600] 123.46.122.168.in-addr.arpa. domain name pointer comm595-0302-123.bu.edu [3600] 124.46.122.168.in-addr.arpa. domain name pointer comm595-0302-124.bu.edu [3600] 125.46.122.168.in-addr.arpa. domain name pointer comm595-0302-125.bu.edu [3600] 126.46.122.168.in-addr.arpa. domain name pointer comm595-0302-126.bu.edu [3600] 127.46.122.168.in-addr.arpa. domain name pointer comm595-0302-127.bu.edu [3600] 128.46.122.168.in-addr.arpa. domain name pointer comm595-0302-128.bu.edu [3600] 129.46.122.168.in-addr.arpa. domain name pointer comm595-0302-129.bu.edu [3600] 130.46.122.168.in-addr.arpa. domain name pointer comm595-0302-130.bu.edu [3600] 131.46.122.168.in-addr.arpa. domain name pointer comm595-0302-131.bu.edu [3600] 132.46.122.168.in-addr.arpa. domain name pointer comm595-0302-132.bu.edu [3600] 133.46.122.168.in-addr.arpa. domain name pointer comm595-0302-133.bu.edu [3600] 134.46.122.168.in-addr.arpa. domain name pointer comm595-0302-134.bu.edu [3600] 135.46.122.168.in-addr.arpa. domain name pointer comm595-0302-135.bu.edu [3600] 136.46.122.168.in-addr.arpa. domain name pointer comm595-0302-136.bu.edu [3600] 137.46.122.168.in-addr.arpa. domain name pointer comm595-0302-137.bu.edu [3600] 138.46.122.168.in-addr.arpa. domain name pointer comm595-0302-138.bu.edu [3600] 139.46.122.168.in-addr.arpa. domain name pointer comm595-0302-139.bu.edu [3600] 140.46.122.168.in-addr.arpa. domain name pointer comm595-0302-140.bu.edu [3600] 141.46.122.168.in-addr.arpa. domain name pointer comm595-0302-141.bu.edu [3600] 142.46.122.168.in-addr.arpa. domain name pointer comm595-0302-142.bu.edu [3600] 143.46.122.168.in-addr.arpa. domain name pointer comm595-0302-143.bu.edu [3600] 144.46.122.168.in-addr.arpa. domain name pointer comm595-0302-144.bu.edu [3600] 145.46.122.168.in-addr.arpa. domain name pointer comm595-0302-145.bu.edu [3600] 146.46.122.168.in-addr.arpa. domain name pointer comm595-0302-146.bu.edu [3600] 147.46.122.168.in-addr.arpa. domain name pointer comm595-0302-147.bu.edu [3600] 148.46.122.168.in-addr.arpa. domain name pointer comm595-0302-148.bu.edu [3600] 149.46.122.168.in-addr.arpa. domain name pointer comm595-0302-149.bu.edu [3600] 150.46.122.168.in-addr.arpa. domain name pointer comm595-0302-150.bu.edu [3600] 151.46.122.168.in-addr.arpa. domain name pointer comm595-0302-151.bu.edu [3600] 152.46.122.168.in-addr.arpa. domain name pointer comm595-0302-152.bu.edu [3600] 153.46.122.168.in-addr.arpa. domain name pointer comm595-0302-153.bu.edu [3600] 154.46.122.168.in-addr.arpa. domain name pointer comm595-0302-154.bu.edu [3600] 155.46.122.168.in-addr.arpa. domain name pointer comm595-0302-155.bu.edu [3600] 156.46.122.168.in-addr.arpa. domain name pointer comm595-0302-156.bu.edu [3600] 157.46.122.168.in-addr.arpa. domain name pointer comm595-0302-157.bu.edu [3600] 158.46.122.168.in-addr.arpa. domain name pointer comm595-0302-158.bu.edu [3600] 159.46.122.168.in-addr.arpa. domain name pointer comm595-0302-159.bu.edu [3600] 160.46.122.168.in-addr.arpa. domain name pointer comm595-0302-160.bu.edu [3600] 161.46.122.168.in-addr.arpa. domain name pointer comm595-0302-161.bu.edu [3600] 162.46.122.168.in-addr.arpa. domain name pointer comm595-0302-162.bu.edu [3600] 163.46.122.168.in-addr.arpa. domain name pointer comm595-0302-163.bu.edu [3600] 164.46.122.168.in-addr.arpa. domain name pointer comm595-0302-164.bu.edu [3600] 165.46.122.168.in-addr.arpa. domain name pointer comm595-0302-165.bu.edu [3600] 166.46.122.168.in-addr.arpa. domain name pointer comm595-0302-166.bu.edu [3600] 167.46.122.168.in-addr.arpa. domain name pointer comm595-0302-167.bu.edu [3600] 168.46.122.168.in-addr.arpa. domain name pointer comm595-0302-168.bu.edu [3600] 169.46.122.168.in-addr.arpa. domain name pointer comm595-0302-169.bu.edu [3600] 170.46.122.168.in-addr.arpa. domain name pointer comm595-0302-170.bu.edu [3600] 171.46.122.168.in-addr.arpa. domain name pointer comm595-0302-171.bu.edu [3600] 172.46.122.168.in-addr.arpa. domain name pointer comm595-0302-172.bu.edu [3600] 173.46.122.168.in-addr.arpa. domain name pointer comm595-0302-173.bu.edu [3600] 174.46.122.168.in-addr.arpa. domain name pointer comm595-0302-174.bu.edu [3600] 175.46.122.168.in-addr.arpa. domain name pointer comm595-0302-175.bu.edu [3600] 176.46.122.168.in-addr.arpa. domain name pointer comm595-0302-176.bu.edu [3600] 177.46.122.168.in-addr.arpa. domain name pointer comm595-0302-177.bu.edu [3600] 178.46.122.168.in-addr.arpa. domain name pointer comm595-0302-178.bu.edu [3600] 179.46.122.168.in-addr.arpa. domain name pointer comm595-0302-179.bu.edu [3600] 180.46.122.168.in-addr.arpa. domain name pointer comm595-0302-180.bu.edu [3600] 181.46.122.168.in-addr.arpa. domain name pointer comm595-0302-181.bu.edu [3600] 182.46.122.168.in-addr.arpa. domain name pointer comm595-0302-182.bu.edu [3600] 183.46.122.168.in-addr.arpa. domain name pointer comm595-0302-183.bu.edu [3600] 184.46.122.168.in-addr.arpa. domain name pointer comm595-0302-184.bu.edu [3600] 185.46.122.168.in-addr.arpa. domain name pointer comm595-0302-185.bu.edu [3600] 186.46.122.168.in-addr.arpa. domain name pointer comm595-0302-186.bu.edu [3600] 187.46.122.168.in-addr.arpa. domain name pointer comm595-0302-187.bu.edu [3600] 188.46.122.168.in-addr.arpa. domain name pointer comm595-0302-188.bu.edu [3600] 189.46.122.168.in-addr.arpa. domain name pointer comm595-0302-189.bu.edu [3600] 190.46.122.168.in-addr.arpa. domain name pointer comm595-0302-190.bu.edu [3600] 191.46.122.168.in-addr.arpa. domain name pointer comm595-0302-191.bu.edu [3600] 192.46.122.168.in-addr.arpa. domain name pointer comm595-0302-192.bu.edu [3600] 193.46.122.168.in-addr.arpa. domain name pointer comm595-0302-193.bu.edu [3600] 194.46.122.168.in-addr.arpa. domain name pointer comm595-0302-194.bu.edu [3600] 195.46.122.168.in-addr.arpa. domain name pointer comm595-0302-195.bu.edu [3600] 196.46.122.168.in-addr.arpa. domain name pointer comm595-0302-196.bu.edu [3600] 197.46.122.168.in-addr.arpa. domain name pointer comm595-0302-197.bu.edu [3600] 198.46.122.168.in-addr.arpa. domain name pointer comm595-0302-198.bu.edu [3600] 199.46.122.168.in-addr.arpa. domain name pointer comm595-0302-199.bu.edu [3600] 200.46.122.168.in-addr.arpa. domain name pointer comm595-0302-200.bu.edu [3600] 201.46.122.168.in-addr.arpa. domain name pointer comm595-0302-201.bu.edu [3600] 202.46.122.168.in-addr.arpa. domain name pointer comm595-0302-202.bu.edu [3600] 203.46.122.168.in-addr.arpa. domain name pointer comm595-0302-203.bu.edu [3600] 204.46.122.168.in-addr.arpa. domain name pointer comm595-0302-204.bu.edu [3600] 205.46.122.168.in-addr.arpa. domain name pointer comm595-0302-205.bu.edu [3600] 206.46.122.168.in-addr.arpa. domain name pointer comm595-0302-206.bu.edu [3600] 207.46.122.168.in-addr.arpa. domain name pointer comm595-0302-207.bu.edu [3600] 208.46.122.168.in-addr.arpa. domain name pointer comm595-0302-208.bu.edu [3600] 209.46.122.168.in-addr.arpa. domain name pointer comm595-0302-209.bu.edu [3600] 210.46.122.168.in-addr.arpa. domain name pointer comm595-0302-210.bu.edu [3600] 211.46.122.168.in-addr.arpa. domain name pointer comm595-0302-211.bu.edu [3600] 212.46.122.168.in-addr.arpa. domain name pointer comm595-0302-212.bu.edu [3600] 213.46.122.168.in-addr.arpa. domain name pointer comm595-0302-213.bu.edu [3600] 214.46.122.168.in-addr.arpa. domain name pointer comm595-0302-214.bu.edu [3600] 215.46.122.168.in-addr.arpa. domain name pointer comm595-0302-215.bu.edu [3600] 216.46.122.168.in-addr.arpa. domain name pointer comm595-0302-216.bu.edu [3600] 217.46.122.168.in-addr.arpa. domain name pointer comm595-0302-217.bu.edu [3600] 218.46.122.168.in-addr.arpa. domain name pointer comm595-0302-218.bu.edu [3600] 219.46.122.168.in-addr.arpa. domain name pointer comm595-0302-219.bu.edu [3600] 220.46.122.168.in-addr.arpa. domain name pointer comm595-0302-220.bu.edu [3600] 221.46.122.168.in-addr.arpa. domain name pointer comm595-0302-221.bu.edu [3600] 222.46.122.168.in-addr.arpa. domain name pointer comm595-0302-222.bu.edu [3600] 223.46.122.168.in-addr.arpa. domain name pointer comm595-0302-223.bu.edu [3600] 224.46.122.168.in-addr.arpa. domain name pointer comm595-0302-224.bu.edu [3600] 225.46.122.168.in-addr.arpa. domain name pointer comm595-0302-225.bu.edu [3600] 226.46.122.168.in-addr.arpa. domain name pointer comm595-0302-226.bu.edu [3600] 227.46.122.168.in-addr.arpa. domain name pointer comm595-0302-227.bu.edu [3600] 228.46.122.168.in-addr.arpa. domain name pointer comm595-0302-228.bu.edu [3600] 229.46.122.168.in-addr.arpa. domain name pointer comm595-0302-229.bu.edu [3600] 230.46.122.168.in-addr.arpa. domain name pointer comm595-0302-230.bu.edu [3600] 231.46.122.168.in-addr.arpa. domain name pointer comm595-0302-231.bu.edu [3600] 232.46.122.168.in-addr.arpa. domain name pointer comm595-0302-232.bu.edu [3600] 233.46.122.168.in-addr.arpa. domain name pointer comm595-0302-233.bu.edu [3600] 234.46.122.168.in-addr.arpa. domain name pointer comm595-0302-234.bu.edu [3600] 235.46.122.168.in-addr.arpa. domain name pointer comm595-0302-235.bu.edu [3600] 236.46.122.168.in-addr.arpa. domain name pointer comm595-0302-236.bu.edu [3600] 237.46.122.168.in-addr.arpa. domain name pointer comm595-0302-237.bu.edu [3600] 238.46.122.168.in-addr.arpa. domain name pointer comm595-0302-238.bu.edu [3600] 239.46.122.168.in-addr.arpa. domain name pointer comm595-0302-239.bu.edu [3600] 240.46.122.168.in-addr.arpa. domain name pointer comm595-0302-240.bu.edu [3600] 241.46.122.168.in-addr.arpa. domain name pointer smgpodium322.bu.edu [3600] 242.46.122.168.in-addr.arpa. domain name pointer smgpodium315.bu.edu [3600] 243.46.122.168.in-addr.arpa. domain name pointer smgpodium302.bu.edu [0] 244.46.122.168.in-addr.arpa.: domain name does not exist [0] 245.46.122.168.in-addr.arpa.: domain name does not exist [0] 246.46.122.168.in-addr.arpa.: domain name does not exist [0] 247.46.122.168.in-addr.arpa.: domain name does not exist [0] 248.46.122.168.in-addr.arpa.: domain name does not exist [0] 249.46.122.168.in-addr.arpa.: domain name does not exist [0] 250.46.122.168.in-addr.arpa.: domain name does not exist [0] 251.46.122.168.in-addr.arpa.: domain name does not exist [0] 252.46.122.168.in-addr.arpa.: domain name does not exist [0] 253.46.122.168.in-addr.arpa.: domain name does not exist [0] 254.46.122.168.in-addr.arpa.: domain name does not exist [0] 255.46.122.168.in-addr.arpa.: domain name does not exist