[0] 0.47.122.168.in-addr.arpa.: domain name does not exist [3600] 1.47.122.168.in-addr.arpa. domain name pointer comm595-0204net-gw.bu.edu [0] 2.47.122.168.in-addr.arpa.: domain name does not exist [0] 3.47.122.168.in-addr.arpa.: domain name does not exist [0] 4.47.122.168.in-addr.arpa.: domain name does not exist [0] 5.47.122.168.in-addr.arpa.: domain name does not exist [0] 6.47.122.168.in-addr.arpa.: domain name does not exist [0] 7.47.122.168.in-addr.arpa.: domain name does not exist [0] 8.47.122.168.in-addr.arpa.: domain name does not exist [0] 9.47.122.168.in-addr.arpa.: domain name does not exist [0] 10.47.122.168.in-addr.arpa.: domain name does not exist [3600] 11.47.122.168.in-addr.arpa. domain name pointer comm595-212aer01.bu.edu [3600] 12.47.122.168.in-addr.arpa. domain name pointer comm595-224aer01.bu.edu [3600] 13.47.122.168.in-addr.arpa. domain name pointer comm595-240aer01.bu.edu [0] 14.47.122.168.in-addr.arpa.: domain name does not exist [0] 15.47.122.168.in-addr.arpa.: domain name does not exist [0] 16.47.122.168.in-addr.arpa.: domain name does not exist [0] 17.47.122.168.in-addr.arpa.: domain name does not exist [0] 18.47.122.168.in-addr.arpa.: domain name does not exist [0] 19.47.122.168.in-addr.arpa.: domain name does not exist [0] 20.47.122.168.in-addr.arpa.: domain name does not exist [0] 21.47.122.168.in-addr.arpa.: domain name does not exist [0] 22.47.122.168.in-addr.arpa.: domain name does not exist [0] 23.47.122.168.in-addr.arpa.: domain name does not exist [0] 24.47.122.168.in-addr.arpa.: domain name does not exist [0] 25.47.122.168.in-addr.arpa.: domain name does not exist [0] 26.47.122.168.in-addr.arpa.: domain name does not exist [0] 27.47.122.168.in-addr.arpa.: domain name does not exist [0] 28.47.122.168.in-addr.arpa.: domain name does not exist [0] 29.47.122.168.in-addr.arpa.: domain name does not exist [0] 30.47.122.168.in-addr.arpa.: domain name does not exist [3600] 31.47.122.168.in-addr.arpa. domain name pointer comm595-0204-031.bu.edu [3600] 32.47.122.168.in-addr.arpa. domain name pointer comm595-0204-032.bu.edu [3600] 33.47.122.168.in-addr.arpa. domain name pointer comm595-0204-033.bu.edu [3600] 34.47.122.168.in-addr.arpa. domain name pointer comm595-0204-034.bu.edu [3600] 35.47.122.168.in-addr.arpa. domain name pointer comm595-0204-035.bu.edu [3600] 36.47.122.168.in-addr.arpa. domain name pointer comm595-0204-036.bu.edu [3600] 37.47.122.168.in-addr.arpa. domain name pointer comm595-0204-037.bu.edu [3600] 38.47.122.168.in-addr.arpa. domain name pointer comm595-0204-038.bu.edu [3600] 39.47.122.168.in-addr.arpa. domain name pointer comm595-0204-039.bu.edu [3600] 40.47.122.168.in-addr.arpa. domain name pointer comm595-0204-040.bu.edu [3600] 41.47.122.168.in-addr.arpa. domain name pointer comm595-0204-041.bu.edu [3600] 42.47.122.168.in-addr.arpa. domain name pointer comm595-0204-042.bu.edu [3600] 43.47.122.168.in-addr.arpa. domain name pointer comm595-0204-043.bu.edu [3600] 44.47.122.168.in-addr.arpa. domain name pointer comm595-0204-044.bu.edu [3600] 45.47.122.168.in-addr.arpa. domain name pointer comm595-0204-045.bu.edu [3600] 46.47.122.168.in-addr.arpa. domain name pointer comm595-0204-046.bu.edu [3600] 47.47.122.168.in-addr.arpa. domain name pointer comm595-0204-047.bu.edu [3600] 48.47.122.168.in-addr.arpa. domain name pointer comm595-0204-048.bu.edu [3600] 49.47.122.168.in-addr.arpa. domain name pointer comm595-0204-049.bu.edu [3600] 50.47.122.168.in-addr.arpa. domain name pointer comm595-0204-050.bu.edu [3600] 51.47.122.168.in-addr.arpa. domain name pointer comm595-0204-051.bu.edu [3600] 52.47.122.168.in-addr.arpa. domain name pointer comm595-0204-052.bu.edu [3600] 53.47.122.168.in-addr.arpa. domain name pointer comm595-0204-053.bu.edu [3600] 54.47.122.168.in-addr.arpa. domain name pointer comm595-0204-054.bu.edu [3600] 55.47.122.168.in-addr.arpa. domain name pointer comm595-0204-055.bu.edu [3600] 56.47.122.168.in-addr.arpa. domain name pointer comm595-0204-056.bu.edu [3600] 57.47.122.168.in-addr.arpa. domain name pointer comm595-0204-057.bu.edu [3600] 58.47.122.168.in-addr.arpa. domain name pointer comm595-0204-058.bu.edu [3600] 59.47.122.168.in-addr.arpa. domain name pointer comm595-0204-059.bu.edu [3600] 60.47.122.168.in-addr.arpa. domain name pointer comm595-0204-060.bu.edu [3600] 61.47.122.168.in-addr.arpa. domain name pointer comm595-0204-061.bu.edu [3600] 62.47.122.168.in-addr.arpa. domain name pointer comm595-0204-062.bu.edu [3600] 63.47.122.168.in-addr.arpa. domain name pointer comm595-0204-063.bu.edu [3600] 64.47.122.168.in-addr.arpa. domain name pointer comm595-0204-064.bu.edu [3600] 65.47.122.168.in-addr.arpa. domain name pointer comm595-0204-065.bu.edu [3600] 66.47.122.168.in-addr.arpa. domain name pointer comm595-0204-066.bu.edu [3600] 67.47.122.168.in-addr.arpa. domain name pointer comm595-0204-067.bu.edu [3600] 68.47.122.168.in-addr.arpa. domain name pointer comm595-0204-068.bu.edu [3600] 69.47.122.168.in-addr.arpa. domain name pointer comm595-0204-069.bu.edu [3600] 70.47.122.168.in-addr.arpa. domain name pointer comm595-0204-070.bu.edu [3600] 71.47.122.168.in-addr.arpa. domain name pointer comm595-0204-071.bu.edu [3600] 72.47.122.168.in-addr.arpa. domain name pointer comm595-0204-072.bu.edu [3600] 73.47.122.168.in-addr.arpa. domain name pointer comm595-0204-073.bu.edu [3600] 74.47.122.168.in-addr.arpa. domain name pointer comm595-0204-074.bu.edu [3600] 75.47.122.168.in-addr.arpa. domain name pointer comm595-0204-075.bu.edu [3600] 76.47.122.168.in-addr.arpa. domain name pointer comm595-0204-076.bu.edu [3600] 77.47.122.168.in-addr.arpa. domain name pointer comm595-0204-077.bu.edu [3600] 78.47.122.168.in-addr.arpa. domain name pointer comm595-0204-078.bu.edu [3600] 79.47.122.168.in-addr.arpa. domain name pointer comm595-0204-079.bu.edu [3600] 80.47.122.168.in-addr.arpa. domain name pointer comm595-0204-080.bu.edu [3600] 81.47.122.168.in-addr.arpa. domain name pointer comm595-0204-081.bu.edu [3600] 82.47.122.168.in-addr.arpa. domain name pointer comm595-0204-082.bu.edu [3600] 83.47.122.168.in-addr.arpa. domain name pointer comm595-0204-083.bu.edu [3600] 84.47.122.168.in-addr.arpa. domain name pointer comm595-0204-084.bu.edu [3600] 85.47.122.168.in-addr.arpa. domain name pointer comm595-0204-085.bu.edu [3600] 86.47.122.168.in-addr.arpa. domain name pointer comm595-0204-086.bu.edu [3600] 87.47.122.168.in-addr.arpa. domain name pointer comm595-0204-087.bu.edu [3600] 88.47.122.168.in-addr.arpa. domain name pointer comm595-0204-088.bu.edu [3600] 89.47.122.168.in-addr.arpa. domain name pointer comm595-0204-089.bu.edu [3600] 90.47.122.168.in-addr.arpa. domain name pointer comm595-0204-090.bu.edu [3600] 91.47.122.168.in-addr.arpa. domain name pointer comm595-0204-091.bu.edu [3600] 92.47.122.168.in-addr.arpa. domain name pointer comm595-0204-092.bu.edu [3600] 93.47.122.168.in-addr.arpa. domain name pointer comm595-0204-093.bu.edu [3600] 94.47.122.168.in-addr.arpa. domain name pointer comm595-0204-094.bu.edu [3600] 95.47.122.168.in-addr.arpa. domain name pointer comm595-0204-095.bu.edu [3600] 96.47.122.168.in-addr.arpa. domain name pointer comm595-0204-096.bu.edu [3600] 97.47.122.168.in-addr.arpa. domain name pointer comm595-0204-097.bu.edu [3600] 98.47.122.168.in-addr.arpa. domain name pointer comm595-0204-098.bu.edu [3600] 99.47.122.168.in-addr.arpa. domain name pointer comm595-0204-099.bu.edu [3600] 100.47.122.168.in-addr.arpa. domain name pointer comm595-0204-100.bu.edu [3600] 101.47.122.168.in-addr.arpa. domain name pointer comm595-0204-101.bu.edu [3600] 102.47.122.168.in-addr.arpa. domain name pointer comm595-0204-102.bu.edu [3600] 103.47.122.168.in-addr.arpa. domain name pointer comm595-0204-103.bu.edu [3600] 104.47.122.168.in-addr.arpa. domain name pointer comm595-0204-104.bu.edu [3600] 105.47.122.168.in-addr.arpa. domain name pointer comm595-0204-105.bu.edu [3600] 106.47.122.168.in-addr.arpa. domain name pointer comm595-0204-106.bu.edu [3600] 107.47.122.168.in-addr.arpa. domain name pointer comm595-0204-107.bu.edu [3600] 108.47.122.168.in-addr.arpa. domain name pointer comm595-0204-108.bu.edu [3600] 109.47.122.168.in-addr.arpa. domain name pointer comm595-0204-109.bu.edu [3600] 110.47.122.168.in-addr.arpa. domain name pointer comm595-0204-110.bu.edu [3600] 111.47.122.168.in-addr.arpa. domain name pointer comm595-0204-111.bu.edu [3600] 112.47.122.168.in-addr.arpa. domain name pointer comm595-0204-112.bu.edu [3600] 113.47.122.168.in-addr.arpa. domain name pointer comm595-0204-113.bu.edu [3600] 114.47.122.168.in-addr.arpa. domain name pointer comm595-0204-114.bu.edu [3600] 115.47.122.168.in-addr.arpa. domain name pointer comm595-0204-115.bu.edu [3600] 116.47.122.168.in-addr.arpa. domain name pointer comm595-0204-116.bu.edu [3600] 117.47.122.168.in-addr.arpa. domain name pointer comm595-0204-117.bu.edu [3600] 118.47.122.168.in-addr.arpa. domain name pointer comm595-0204-118.bu.edu [3600] 119.47.122.168.in-addr.arpa. domain name pointer comm595-0204-119.bu.edu [3600] 120.47.122.168.in-addr.arpa. domain name pointer comm595-0204-120.bu.edu [3600] 121.47.122.168.in-addr.arpa. domain name pointer comm595-0204-121.bu.edu [3600] 122.47.122.168.in-addr.arpa. domain name pointer comm595-0204-122.bu.edu [3600] 123.47.122.168.in-addr.arpa. domain name pointer comm595-0204-123.bu.edu [3600] 124.47.122.168.in-addr.arpa. domain name pointer comm595-0204-124.bu.edu [3600] 125.47.122.168.in-addr.arpa. domain name pointer comm595-0204-125.bu.edu [3600] 126.47.122.168.in-addr.arpa. domain name pointer comm595-0204-126.bu.edu [3600] 127.47.122.168.in-addr.arpa. domain name pointer comm595-0204-127.bu.edu [3600] 128.47.122.168.in-addr.arpa. domain name pointer comm595-0204-128.bu.edu [3600] 129.47.122.168.in-addr.arpa. domain name pointer comm595-0204-129.bu.edu [3600] 130.47.122.168.in-addr.arpa. domain name pointer comm595-0204-130.bu.edu [3600] 131.47.122.168.in-addr.arpa. domain name pointer comm595-0204-131.bu.edu [3600] 132.47.122.168.in-addr.arpa. domain name pointer comm595-0204-132.bu.edu [3600] 133.47.122.168.in-addr.arpa. domain name pointer comm595-0204-133.bu.edu [3600] 134.47.122.168.in-addr.arpa. domain name pointer comm595-0204-134.bu.edu [3600] 135.47.122.168.in-addr.arpa. domain name pointer comm595-0204-135.bu.edu [3600] 136.47.122.168.in-addr.arpa. domain name pointer comm595-0204-136.bu.edu [3600] 137.47.122.168.in-addr.arpa. domain name pointer comm595-0204-137.bu.edu [3600] 138.47.122.168.in-addr.arpa. domain name pointer comm595-0204-138.bu.edu [3600] 139.47.122.168.in-addr.arpa. domain name pointer comm595-0204-139.bu.edu [3600] 140.47.122.168.in-addr.arpa. domain name pointer comm595-0204-140.bu.edu [3600] 141.47.122.168.in-addr.arpa. domain name pointer comm595-0204-141.bu.edu [3600] 142.47.122.168.in-addr.arpa. domain name pointer comm595-0204-142.bu.edu [3600] 143.47.122.168.in-addr.arpa. domain name pointer comm595-0204-143.bu.edu [3600] 144.47.122.168.in-addr.arpa. domain name pointer comm595-0204-144.bu.edu [3600] 145.47.122.168.in-addr.arpa. domain name pointer comm595-0204-145.bu.edu [3600] 146.47.122.168.in-addr.arpa. domain name pointer comm595-0204-146.bu.edu [3600] 147.47.122.168.in-addr.arpa. domain name pointer comm595-0204-147.bu.edu [3600] 148.47.122.168.in-addr.arpa. domain name pointer comm595-0204-148.bu.edu [3600] 149.47.122.168.in-addr.arpa. domain name pointer comm595-0204-149.bu.edu [3600] 150.47.122.168.in-addr.arpa. domain name pointer comm595-0204-150.bu.edu [3600] 151.47.122.168.in-addr.arpa. domain name pointer comm595-0204-151.bu.edu [3600] 152.47.122.168.in-addr.arpa. domain name pointer comm595-0204-152.bu.edu [3600] 153.47.122.168.in-addr.arpa. domain name pointer comm595-0204-153.bu.edu [3600] 154.47.122.168.in-addr.arpa. domain name pointer comm595-0204-154.bu.edu [3600] 155.47.122.168.in-addr.arpa. domain name pointer comm595-0204-155.bu.edu [3600] 156.47.122.168.in-addr.arpa. domain name pointer comm595-0204-156.bu.edu [3600] 157.47.122.168.in-addr.arpa. domain name pointer comm595-0204-157.bu.edu [3600] 158.47.122.168.in-addr.arpa. domain name pointer comm595-0204-158.bu.edu [3600] 159.47.122.168.in-addr.arpa. domain name pointer comm595-0204-159.bu.edu [3600] 160.47.122.168.in-addr.arpa. domain name pointer comm595-0204-160.bu.edu [3600] 161.47.122.168.in-addr.arpa. domain name pointer comm595-0204-161.bu.edu [3600] 162.47.122.168.in-addr.arpa. domain name pointer comm595-0204-162.bu.edu [3600] 163.47.122.168.in-addr.arpa. domain name pointer comm595-0204-163.bu.edu [3600] 164.47.122.168.in-addr.arpa. domain name pointer comm595-0204-164.bu.edu [3600] 165.47.122.168.in-addr.arpa. domain name pointer comm595-0204-165.bu.edu [3600] 166.47.122.168.in-addr.arpa. domain name pointer comm595-0204-166.bu.edu [3600] 167.47.122.168.in-addr.arpa. domain name pointer comm595-0204-167.bu.edu [3600] 168.47.122.168.in-addr.arpa. domain name pointer comm595-0204-168.bu.edu [3600] 169.47.122.168.in-addr.arpa. domain name pointer comm595-0204-169.bu.edu [3600] 170.47.122.168.in-addr.arpa. domain name pointer comm595-0204-170.bu.edu [3600] 171.47.122.168.in-addr.arpa. domain name pointer comm595-0204-171.bu.edu [3600] 172.47.122.168.in-addr.arpa. domain name pointer comm595-0204-172.bu.edu [3600] 173.47.122.168.in-addr.arpa. domain name pointer comm595-0204-173.bu.edu [3600] 174.47.122.168.in-addr.arpa. domain name pointer comm595-0204-174.bu.edu [3600] 175.47.122.168.in-addr.arpa. domain name pointer comm595-0204-175.bu.edu [3600] 176.47.122.168.in-addr.arpa. domain name pointer comm595-0204-176.bu.edu [3600] 177.47.122.168.in-addr.arpa. domain name pointer comm595-0204-177.bu.edu [3600] 178.47.122.168.in-addr.arpa. domain name pointer comm595-0204-178.bu.edu [3600] 179.47.122.168.in-addr.arpa. domain name pointer comm595-0204-179.bu.edu [3600] 180.47.122.168.in-addr.arpa. domain name pointer comm595-0204-180.bu.edu [3600] 181.47.122.168.in-addr.arpa. domain name pointer comm595-0204-181.bu.edu [3600] 182.47.122.168.in-addr.arpa. domain name pointer comm595-0204-182.bu.edu [3600] 183.47.122.168.in-addr.arpa. domain name pointer comm595-0204-183.bu.edu [3600] 184.47.122.168.in-addr.arpa. domain name pointer comm595-0204-184.bu.edu [3600] 185.47.122.168.in-addr.arpa. domain name pointer comm595-0204-185.bu.edu [3600] 186.47.122.168.in-addr.arpa. domain name pointer comm595-0204-186.bu.edu [3600] 187.47.122.168.in-addr.arpa. domain name pointer comm595-0204-187.bu.edu [3600] 188.47.122.168.in-addr.arpa. domain name pointer comm595-0204-188.bu.edu [3600] 189.47.122.168.in-addr.arpa. domain name pointer comm595-0204-189.bu.edu [3600] 190.47.122.168.in-addr.arpa. domain name pointer comm595-0204-190.bu.edu [3600] 191.47.122.168.in-addr.arpa. domain name pointer comm595-0204-191.bu.edu [3600] 192.47.122.168.in-addr.arpa. domain name pointer comm595-0204-192.bu.edu [3600] 193.47.122.168.in-addr.arpa. domain name pointer comm595-0204-193.bu.edu [3600] 194.47.122.168.in-addr.arpa. domain name pointer comm595-0204-194.bu.edu [3600] 195.47.122.168.in-addr.arpa. domain name pointer comm595-0204-195.bu.edu [3600] 196.47.122.168.in-addr.arpa. domain name pointer comm595-0204-196.bu.edu [3600] 197.47.122.168.in-addr.arpa. domain name pointer comm595-0204-197.bu.edu [3600] 198.47.122.168.in-addr.arpa. domain name pointer comm595-0204-198.bu.edu [3600] 199.47.122.168.in-addr.arpa. domain name pointer comm595-0204-199.bu.edu [3600] 200.47.122.168.in-addr.arpa. domain name pointer comm595-0204-200.bu.edu [3600] 201.47.122.168.in-addr.arpa. domain name pointer comm595-0204-201.bu.edu [3600] 202.47.122.168.in-addr.arpa. domain name pointer comm595-0204-202.bu.edu [3600] 203.47.122.168.in-addr.arpa. domain name pointer comm595-0204-203.bu.edu [3600] 204.47.122.168.in-addr.arpa. domain name pointer comm595-0204-204.bu.edu [3600] 205.47.122.168.in-addr.arpa. domain name pointer comm595-0204-205.bu.edu [3600] 206.47.122.168.in-addr.arpa. domain name pointer comm595-0204-206.bu.edu [3600] 207.47.122.168.in-addr.arpa. domain name pointer comm595-0204-207.bu.edu [3600] 208.47.122.168.in-addr.arpa. domain name pointer comm595-0204-208.bu.edu [3600] 209.47.122.168.in-addr.arpa. domain name pointer comm595-0204-209.bu.edu [3600] 210.47.122.168.in-addr.arpa. domain name pointer comm595-0204-210.bu.edu [3600] 211.47.122.168.in-addr.arpa. domain name pointer comm595-0204-211.bu.edu [3600] 212.47.122.168.in-addr.arpa. domain name pointer comm595-0204-212.bu.edu [3600] 213.47.122.168.in-addr.arpa. domain name pointer comm595-0204-213.bu.edu [3600] 214.47.122.168.in-addr.arpa. domain name pointer comm595-0204-214.bu.edu [3600] 215.47.122.168.in-addr.arpa. domain name pointer comm595-0204-215.bu.edu [3600] 216.47.122.168.in-addr.arpa. domain name pointer comm595-0204-216.bu.edu [3600] 217.47.122.168.in-addr.arpa. domain name pointer comm595-0204-217.bu.edu [3600] 218.47.122.168.in-addr.arpa. domain name pointer comm595-0204-218.bu.edu [3600] 219.47.122.168.in-addr.arpa. domain name pointer comm595-0204-219.bu.edu [3600] 220.47.122.168.in-addr.arpa. domain name pointer comm595-0204-220.bu.edu [3600] 221.47.122.168.in-addr.arpa. domain name pointer comm595-0204-221.bu.edu [3600] 222.47.122.168.in-addr.arpa. domain name pointer comm595-0204-222.bu.edu [3600] 223.47.122.168.in-addr.arpa. domain name pointer comm595-0204-223.bu.edu [3600] 224.47.122.168.in-addr.arpa. domain name pointer comm595-0204-224.bu.edu [3600] 225.47.122.168.in-addr.arpa. domain name pointer comm595-0204-225.bu.edu [3600] 226.47.122.168.in-addr.arpa. domain name pointer comm595-0204-226.bu.edu [3600] 227.47.122.168.in-addr.arpa. domain name pointer comm595-0204-227.bu.edu [3600] 228.47.122.168.in-addr.arpa. domain name pointer comm595-0204-228.bu.edu [3600] 229.47.122.168.in-addr.arpa. domain name pointer comm595-0204-229.bu.edu [3600] 230.47.122.168.in-addr.arpa. domain name pointer comm595-0204-230.bu.edu [3600] 231.47.122.168.in-addr.arpa. domain name pointer comm595-0204-231.bu.edu [3600] 232.47.122.168.in-addr.arpa. domain name pointer comm595-0204-232.bu.edu [3600] 233.47.122.168.in-addr.arpa. domain name pointer comm595-0204-233.bu.edu [3600] 234.47.122.168.in-addr.arpa. domain name pointer comm595-0204-234.bu.edu [3600] 235.47.122.168.in-addr.arpa. domain name pointer comm595-0204-235.bu.edu [3600] 236.47.122.168.in-addr.arpa. domain name pointer comm595-0204-236.bu.edu [3600] 237.47.122.168.in-addr.arpa. domain name pointer comm595-0204-237.bu.edu [3600] 238.47.122.168.in-addr.arpa. domain name pointer comm595-0204-238.bu.edu [3600] 239.47.122.168.in-addr.arpa. domain name pointer comm595-0204-239.bu.edu [3600] 240.47.122.168.in-addr.arpa. domain name pointer comm595-0204-240.bu.edu [3600] 241.47.122.168.in-addr.arpa. domain name pointer smgpodium240.bu.edu [3600] 242.47.122.168.in-addr.arpa. domain name pointer smgpodium224.bu.edu [3600] 243.47.122.168.in-addr.arpa. domain name pointer smgpodium212.bu.edu [0] 244.47.122.168.in-addr.arpa.: domain name does not exist [0] 245.47.122.168.in-addr.arpa.: domain name does not exist [0] 246.47.122.168.in-addr.arpa.: domain name does not exist [0] 247.47.122.168.in-addr.arpa.: domain name does not exist [0] 248.47.122.168.in-addr.arpa.: domain name does not exist [0] 249.47.122.168.in-addr.arpa.: domain name does not exist [0] 250.47.122.168.in-addr.arpa.: domain name does not exist [0] 251.47.122.168.in-addr.arpa.: domain name does not exist [0] 252.47.122.168.in-addr.arpa.: domain name does not exist [0] 253.47.122.168.in-addr.arpa.: domain name does not exist [0] 254.47.122.168.in-addr.arpa.: domain name does not exist [0] 255.47.122.168.in-addr.arpa.: domain name does not exist