[0] 0.44.122.168.in-addr.arpa.: domain name does not exist [3600] 1.44.122.168.in-addr.arpa. domain name pointer comm595-0304net-gw.bu.edu [0] 2.44.122.168.in-addr.arpa.: domain name does not exist [0] 3.44.122.168.in-addr.arpa.: domain name does not exist [0] 4.44.122.168.in-addr.arpa.: domain name does not exist [0] 5.44.122.168.in-addr.arpa.: domain name does not exist [0] 6.44.122.168.in-addr.arpa.: domain name does not exist [0] 7.44.122.168.in-addr.arpa.: domain name does not exist [0] 8.44.122.168.in-addr.arpa.: domain name does not exist [0] 9.44.122.168.in-addr.arpa.: domain name does not exist [0] 10.44.122.168.in-addr.arpa.: domain name does not exist [3600] 11.44.122.168.in-addr.arpa. domain name pointer comm595-312aer01.bu.edu [3600] 12.44.122.168.in-addr.arpa. domain name pointer comm595-312ber01.bu.edu [3600] 13.44.122.168.in-addr.arpa. domain name pointer comm595-324ber01.bu.edu [0] 14.44.122.168.in-addr.arpa.: domain name does not exist [0] 15.44.122.168.in-addr.arpa.: domain name does not exist [0] 16.44.122.168.in-addr.arpa.: domain name does not exist [0] 17.44.122.168.in-addr.arpa.: domain name does not exist [0] 18.44.122.168.in-addr.arpa.: domain name does not exist [0] 19.44.122.168.in-addr.arpa.: domain name does not exist [0] 20.44.122.168.in-addr.arpa.: domain name does not exist [0] 21.44.122.168.in-addr.arpa.: domain name does not exist [0] 22.44.122.168.in-addr.arpa.: domain name does not exist [0] 23.44.122.168.in-addr.arpa.: domain name does not exist [0] 24.44.122.168.in-addr.arpa.: domain name does not exist [0] 25.44.122.168.in-addr.arpa.: domain name does not exist [0] 26.44.122.168.in-addr.arpa.: domain name does not exist [0] 27.44.122.168.in-addr.arpa.: domain name does not exist [0] 28.44.122.168.in-addr.arpa.: domain name does not exist [0] 29.44.122.168.in-addr.arpa.: domain name does not exist [0] 30.44.122.168.in-addr.arpa.: domain name does not exist [3600] 31.44.122.168.in-addr.arpa. domain name pointer comm595-0344-031.bu.edu [3600] 32.44.122.168.in-addr.arpa. domain name pointer comm595-0344-032.bu.edu [3600] 33.44.122.168.in-addr.arpa. domain name pointer comm595-0344-033.bu.edu [3600] 34.44.122.168.in-addr.arpa. domain name pointer comm595-0344-034.bu.edu [3600] 35.44.122.168.in-addr.arpa. domain name pointer comm595-0344-035.bu.edu [3600] 36.44.122.168.in-addr.arpa. domain name pointer comm595-0344-036.bu.edu [3600] 37.44.122.168.in-addr.arpa. domain name pointer comm595-0344-037.bu.edu [3600] 38.44.122.168.in-addr.arpa. domain name pointer comm595-0344-038.bu.edu [3600] 39.44.122.168.in-addr.arpa. domain name pointer comm595-0344-039.bu.edu [3600] 40.44.122.168.in-addr.arpa. domain name pointer comm595-0344-040.bu.edu [3600] 41.44.122.168.in-addr.arpa. domain name pointer comm595-0344-041.bu.edu [3600] 42.44.122.168.in-addr.arpa. domain name pointer comm595-0344-042.bu.edu [3600] 43.44.122.168.in-addr.arpa. domain name pointer comm595-0344-043.bu.edu [3600] 44.44.122.168.in-addr.arpa. domain name pointer comm595-0344-044.bu.edu [3600] 45.44.122.168.in-addr.arpa. domain name pointer comm595-0344-045.bu.edu [3600] 46.44.122.168.in-addr.arpa. domain name pointer comm595-0344-046.bu.edu [3600] 47.44.122.168.in-addr.arpa. domain name pointer comm595-0344-047.bu.edu [3600] 48.44.122.168.in-addr.arpa. domain name pointer comm595-0344-048.bu.edu [3600] 49.44.122.168.in-addr.arpa. domain name pointer comm595-0344-049.bu.edu [3600] 50.44.122.168.in-addr.arpa. domain name pointer comm595-0344-050.bu.edu [3600] 51.44.122.168.in-addr.arpa. domain name pointer comm595-0344-051.bu.edu [3600] 52.44.122.168.in-addr.arpa. domain name pointer comm595-0344-052.bu.edu [3600] 53.44.122.168.in-addr.arpa. domain name pointer comm595-0344-053.bu.edu [3600] 54.44.122.168.in-addr.arpa. domain name pointer comm595-0344-054.bu.edu [3600] 55.44.122.168.in-addr.arpa. domain name pointer comm595-0344-055.bu.edu [3600] 56.44.122.168.in-addr.arpa. domain name pointer comm595-0344-056.bu.edu [3600] 57.44.122.168.in-addr.arpa. domain name pointer comm595-0344-057.bu.edu [3600] 58.44.122.168.in-addr.arpa. domain name pointer comm595-0344-058.bu.edu [3600] 59.44.122.168.in-addr.arpa. domain name pointer comm595-0344-059.bu.edu [3600] 60.44.122.168.in-addr.arpa. domain name pointer comm595-0344-060.bu.edu [3600] 61.44.122.168.in-addr.arpa. domain name pointer comm595-0344-061.bu.edu [3600] 62.44.122.168.in-addr.arpa. domain name pointer comm595-0344-062.bu.edu [3600] 63.44.122.168.in-addr.arpa. domain name pointer comm595-0344-063.bu.edu [3600] 64.44.122.168.in-addr.arpa. domain name pointer comm595-0344-064.bu.edu [3600] 65.44.122.168.in-addr.arpa. domain name pointer comm595-0344-065.bu.edu [3600] 66.44.122.168.in-addr.arpa. domain name pointer comm595-0344-066.bu.edu [3600] 67.44.122.168.in-addr.arpa. domain name pointer comm595-0344-067.bu.edu [3600] 68.44.122.168.in-addr.arpa. domain name pointer comm595-0344-068.bu.edu [3600] 69.44.122.168.in-addr.arpa. domain name pointer comm595-0344-069.bu.edu [3600] 70.44.122.168.in-addr.arpa. domain name pointer comm595-0344-070.bu.edu [3600] 71.44.122.168.in-addr.arpa. domain name pointer comm595-0344-071.bu.edu [3600] 72.44.122.168.in-addr.arpa. domain name pointer comm595-0344-072.bu.edu [3600] 73.44.122.168.in-addr.arpa. domain name pointer comm595-0344-073.bu.edu [3600] 74.44.122.168.in-addr.arpa. domain name pointer comm595-0344-074.bu.edu [3600] 75.44.122.168.in-addr.arpa. domain name pointer comm595-0344-075.bu.edu [3600] 76.44.122.168.in-addr.arpa. domain name pointer comm595-0344-076.bu.edu [3600] 77.44.122.168.in-addr.arpa. domain name pointer comm595-0344-077.bu.edu [3600] 78.44.122.168.in-addr.arpa. domain name pointer comm595-0344-078.bu.edu [3600] 79.44.122.168.in-addr.arpa. domain name pointer comm595-0344-079.bu.edu [3600] 80.44.122.168.in-addr.arpa. domain name pointer comm595-0344-080.bu.edu [3600] 81.44.122.168.in-addr.arpa. domain name pointer comm595-0344-081.bu.edu [3600] 82.44.122.168.in-addr.arpa. domain name pointer comm595-0344-082.bu.edu [3600] 83.44.122.168.in-addr.arpa. domain name pointer comm595-0344-083.bu.edu [3600] 84.44.122.168.in-addr.arpa. domain name pointer comm595-0344-084.bu.edu [3600] 85.44.122.168.in-addr.arpa. domain name pointer comm595-0344-085.bu.edu [3600] 86.44.122.168.in-addr.arpa. domain name pointer comm595-0344-086.bu.edu [3600] 87.44.122.168.in-addr.arpa. domain name pointer comm595-0344-087.bu.edu [3600] 88.44.122.168.in-addr.arpa. domain name pointer comm595-0344-088.bu.edu [3600] 89.44.122.168.in-addr.arpa. domain name pointer comm595-0344-089.bu.edu [3600] 90.44.122.168.in-addr.arpa. domain name pointer comm595-0344-090.bu.edu [3600] 91.44.122.168.in-addr.arpa. domain name pointer comm595-0344-091.bu.edu [3600] 92.44.122.168.in-addr.arpa. domain name pointer comm595-0344-092.bu.edu [3600] 93.44.122.168.in-addr.arpa. domain name pointer comm595-0344-093.bu.edu [3600] 94.44.122.168.in-addr.arpa. domain name pointer comm595-0344-094.bu.edu [3600] 95.44.122.168.in-addr.arpa. domain name pointer comm595-0344-095.bu.edu [3600] 96.44.122.168.in-addr.arpa. domain name pointer comm595-0344-096.bu.edu [3600] 97.44.122.168.in-addr.arpa. domain name pointer comm595-0344-097.bu.edu [3600] 98.44.122.168.in-addr.arpa. domain name pointer comm595-0344-098.bu.edu [3600] 99.44.122.168.in-addr.arpa. domain name pointer comm595-0344-099.bu.edu [3600] 100.44.122.168.in-addr.arpa. domain name pointer comm595-0344-100.bu.edu [3600] 101.44.122.168.in-addr.arpa. domain name pointer comm595-0344-101.bu.edu [3600] 102.44.122.168.in-addr.arpa. domain name pointer comm595-0344-102.bu.edu [3600] 103.44.122.168.in-addr.arpa. domain name pointer comm595-0344-103.bu.edu [3600] 104.44.122.168.in-addr.arpa. domain name pointer comm595-0344-104.bu.edu [3600] 105.44.122.168.in-addr.arpa. domain name pointer comm595-0344-105.bu.edu [3600] 106.44.122.168.in-addr.arpa. domain name pointer comm595-0344-106.bu.edu [3600] 107.44.122.168.in-addr.arpa. domain name pointer comm595-0344-107.bu.edu [3600] 108.44.122.168.in-addr.arpa. domain name pointer comm595-0344-108.bu.edu [3600] 109.44.122.168.in-addr.arpa. domain name pointer comm595-0344-109.bu.edu [3600] 110.44.122.168.in-addr.arpa. domain name pointer comm595-0344-110.bu.edu [3600] 111.44.122.168.in-addr.arpa. domain name pointer comm595-0344-111.bu.edu [3600] 112.44.122.168.in-addr.arpa. domain name pointer comm595-0344-112.bu.edu [3600] 113.44.122.168.in-addr.arpa. domain name pointer comm595-0344-113.bu.edu [3600] 114.44.122.168.in-addr.arpa. domain name pointer comm595-0344-114.bu.edu [3600] 115.44.122.168.in-addr.arpa. domain name pointer comm595-0344-115.bu.edu [3600] 116.44.122.168.in-addr.arpa. domain name pointer comm595-0344-116.bu.edu [3600] 117.44.122.168.in-addr.arpa. domain name pointer comm595-0344-117.bu.edu [3600] 118.44.122.168.in-addr.arpa. domain name pointer comm595-0344-118.bu.edu [3600] 119.44.122.168.in-addr.arpa. domain name pointer comm595-0344-119.bu.edu [3600] 120.44.122.168.in-addr.arpa. domain name pointer comm595-0344-120.bu.edu [3600] 121.44.122.168.in-addr.arpa. domain name pointer comm595-0344-121.bu.edu [3600] 122.44.122.168.in-addr.arpa. domain name pointer comm595-0344-122.bu.edu [3600] 123.44.122.168.in-addr.arpa. domain name pointer comm595-0344-123.bu.edu [3600] 124.44.122.168.in-addr.arpa. domain name pointer comm595-0344-124.bu.edu [3600] 125.44.122.168.in-addr.arpa. domain name pointer comm595-0344-125.bu.edu [3600] 126.44.122.168.in-addr.arpa. domain name pointer comm595-0344-126.bu.edu [3600] 127.44.122.168.in-addr.arpa. domain name pointer comm595-0344-127.bu.edu [3600] 128.44.122.168.in-addr.arpa. domain name pointer comm595-0344-128.bu.edu [3600] 129.44.122.168.in-addr.arpa. domain name pointer comm595-0344-129.bu.edu [3600] 130.44.122.168.in-addr.arpa. domain name pointer comm595-0344-130.bu.edu [3600] 131.44.122.168.in-addr.arpa. domain name pointer comm595-0344-131.bu.edu [3600] 132.44.122.168.in-addr.arpa. domain name pointer comm595-0344-132.bu.edu [3600] 133.44.122.168.in-addr.arpa. domain name pointer comm595-0344-133.bu.edu [3600] 134.44.122.168.in-addr.arpa. domain name pointer comm595-0344-134.bu.edu [3600] 135.44.122.168.in-addr.arpa. domain name pointer comm595-0344-135.bu.edu [3600] 136.44.122.168.in-addr.arpa. domain name pointer comm595-0344-136.bu.edu [3600] 137.44.122.168.in-addr.arpa. domain name pointer comm595-0344-137.bu.edu [3600] 138.44.122.168.in-addr.arpa. domain name pointer comm595-0344-138.bu.edu [3600] 139.44.122.168.in-addr.arpa. domain name pointer comm595-0344-139.bu.edu [3600] 140.44.122.168.in-addr.arpa. domain name pointer comm595-0344-140.bu.edu [3600] 141.44.122.168.in-addr.arpa. domain name pointer comm595-0344-141.bu.edu [3600] 142.44.122.168.in-addr.arpa. domain name pointer comm595-0344-142.bu.edu [3600] 143.44.122.168.in-addr.arpa. domain name pointer comm595-0344-143.bu.edu [3600] 144.44.122.168.in-addr.arpa. domain name pointer comm595-0344-144.bu.edu [3600] 145.44.122.168.in-addr.arpa. domain name pointer comm595-0344-145.bu.edu [3600] 146.44.122.168.in-addr.arpa. domain name pointer comm595-0344-146.bu.edu [3600] 147.44.122.168.in-addr.arpa. domain name pointer comm595-0344-147.bu.edu [3600] 148.44.122.168.in-addr.arpa. domain name pointer comm595-0344-148.bu.edu [3600] 149.44.122.168.in-addr.arpa. domain name pointer comm595-0344-149.bu.edu [3600] 150.44.122.168.in-addr.arpa. domain name pointer comm595-0344-150.bu.edu [3600] 151.44.122.168.in-addr.arpa. domain name pointer comm595-0344-151.bu.edu [3600] 152.44.122.168.in-addr.arpa. domain name pointer comm595-0344-152.bu.edu [3600] 153.44.122.168.in-addr.arpa. domain name pointer comm595-0344-153.bu.edu [3600] 154.44.122.168.in-addr.arpa. domain name pointer comm595-0344-154.bu.edu [3600] 155.44.122.168.in-addr.arpa. domain name pointer comm595-0344-155.bu.edu [3600] 156.44.122.168.in-addr.arpa. domain name pointer comm595-0344-156.bu.edu [3600] 157.44.122.168.in-addr.arpa. domain name pointer comm595-0344-157.bu.edu [3600] 158.44.122.168.in-addr.arpa. domain name pointer comm595-0344-158.bu.edu [3600] 159.44.122.168.in-addr.arpa. domain name pointer comm595-0344-159.bu.edu [3600] 160.44.122.168.in-addr.arpa. domain name pointer comm595-0344-160.bu.edu [3600] 161.44.122.168.in-addr.arpa. domain name pointer comm595-0344-161.bu.edu [3600] 162.44.122.168.in-addr.arpa. domain name pointer comm595-0344-162.bu.edu [3600] 163.44.122.168.in-addr.arpa. domain name pointer comm595-0344-163.bu.edu [3600] 164.44.122.168.in-addr.arpa. domain name pointer comm595-0344-164.bu.edu [3600] 165.44.122.168.in-addr.arpa. domain name pointer comm595-0344-165.bu.edu [3600] 166.44.122.168.in-addr.arpa. domain name pointer comm595-0344-166.bu.edu [3600] 167.44.122.168.in-addr.arpa. domain name pointer comm595-0344-167.bu.edu [3600] 168.44.122.168.in-addr.arpa. domain name pointer comm595-0344-168.bu.edu [3600] 169.44.122.168.in-addr.arpa. domain name pointer comm595-0344-169.bu.edu [3600] 170.44.122.168.in-addr.arpa. domain name pointer comm595-0344-170.bu.edu [3600] 171.44.122.168.in-addr.arpa. domain name pointer comm595-0344-171.bu.edu [3600] 172.44.122.168.in-addr.arpa. domain name pointer comm595-0344-172.bu.edu [3600] 173.44.122.168.in-addr.arpa. domain name pointer comm595-0344-173.bu.edu [3600] 174.44.122.168.in-addr.arpa. domain name pointer comm595-0344-174.bu.edu [3600] 175.44.122.168.in-addr.arpa. domain name pointer comm595-0344-175.bu.edu [3600] 176.44.122.168.in-addr.arpa. domain name pointer comm595-0344-176.bu.edu [3600] 177.44.122.168.in-addr.arpa. domain name pointer comm595-0344-177.bu.edu [3600] 178.44.122.168.in-addr.arpa. domain name pointer comm595-0344-178.bu.edu [3600] 179.44.122.168.in-addr.arpa. domain name pointer comm595-0344-179.bu.edu [3600] 180.44.122.168.in-addr.arpa. domain name pointer comm595-0344-180.bu.edu [3600] 181.44.122.168.in-addr.arpa. domain name pointer comm595-0344-181.bu.edu [3600] 182.44.122.168.in-addr.arpa. domain name pointer comm595-0344-182.bu.edu [3600] 183.44.122.168.in-addr.arpa. domain name pointer comm595-0344-183.bu.edu [3600] 184.44.122.168.in-addr.arpa. domain name pointer comm595-0344-184.bu.edu [3600] 185.44.122.168.in-addr.arpa. domain name pointer comm595-0344-185.bu.edu [3600] 186.44.122.168.in-addr.arpa. domain name pointer comm595-0344-186.bu.edu [3600] 187.44.122.168.in-addr.arpa. domain name pointer comm595-0344-187.bu.edu [3600] 188.44.122.168.in-addr.arpa. domain name pointer comm595-0344-188.bu.edu [3600] 189.44.122.168.in-addr.arpa. domain name pointer comm595-0344-189.bu.edu [3600] 190.44.122.168.in-addr.arpa. domain name pointer comm595-0344-190.bu.edu [3600] 191.44.122.168.in-addr.arpa. domain name pointer comm595-0344-191.bu.edu [3600] 192.44.122.168.in-addr.arpa. domain name pointer comm595-0344-192.bu.edu [3600] 193.44.122.168.in-addr.arpa. domain name pointer comm595-0344-193.bu.edu [3600] 194.44.122.168.in-addr.arpa. domain name pointer comm595-0344-194.bu.edu [3600] 195.44.122.168.in-addr.arpa. domain name pointer comm595-0344-195.bu.edu [3600] 196.44.122.168.in-addr.arpa. domain name pointer comm595-0344-196.bu.edu [3600] 197.44.122.168.in-addr.arpa. domain name pointer comm595-0344-197.bu.edu [3600] 198.44.122.168.in-addr.arpa. domain name pointer comm595-0344-198.bu.edu [3600] 199.44.122.168.in-addr.arpa. domain name pointer comm595-0344-199.bu.edu [3600] 200.44.122.168.in-addr.arpa. domain name pointer comm595-0344-200.bu.edu [3600] 201.44.122.168.in-addr.arpa. domain name pointer comm595-0344-201.bu.edu [3600] 202.44.122.168.in-addr.arpa. domain name pointer comm595-0344-202.bu.edu [3600] 203.44.122.168.in-addr.arpa. domain name pointer comm595-0344-203.bu.edu [3600] 204.44.122.168.in-addr.arpa. domain name pointer comm595-0344-204.bu.edu [3600] 205.44.122.168.in-addr.arpa. domain name pointer comm595-0344-205.bu.edu [3600] 206.44.122.168.in-addr.arpa. domain name pointer comm595-0344-206.bu.edu [3600] 207.44.122.168.in-addr.arpa. domain name pointer comm595-0344-207.bu.edu [3600] 208.44.122.168.in-addr.arpa. domain name pointer comm595-0344-208.bu.edu [3600] 209.44.122.168.in-addr.arpa. domain name pointer comm595-0344-209.bu.edu [3600] 210.44.122.168.in-addr.arpa. domain name pointer comm595-0344-210.bu.edu [3600] 211.44.122.168.in-addr.arpa. domain name pointer comm595-0344-211.bu.edu [3600] 212.44.122.168.in-addr.arpa. domain name pointer comm595-0344-212.bu.edu [3600] 213.44.122.168.in-addr.arpa. domain name pointer comm595-0344-213.bu.edu [3600] 214.44.122.168.in-addr.arpa. domain name pointer comm595-0344-214.bu.edu [3600] 215.44.122.168.in-addr.arpa. domain name pointer comm595-0344-215.bu.edu [3600] 216.44.122.168.in-addr.arpa. domain name pointer comm595-0344-216.bu.edu [3600] 217.44.122.168.in-addr.arpa. domain name pointer comm595-0344-217.bu.edu [3600] 218.44.122.168.in-addr.arpa. domain name pointer comm595-0344-218.bu.edu [3600] 219.44.122.168.in-addr.arpa. domain name pointer comm595-0344-219.bu.edu [3600] 220.44.122.168.in-addr.arpa. domain name pointer comm595-0344-220.bu.edu [3600] 221.44.122.168.in-addr.arpa. domain name pointer comm595-0344-221.bu.edu [3600] 222.44.122.168.in-addr.arpa. domain name pointer comm595-0344-222.bu.edu [3600] 223.44.122.168.in-addr.arpa. domain name pointer comm595-0344-223.bu.edu [3600] 224.44.122.168.in-addr.arpa. domain name pointer comm595-0344-224.bu.edu [3600] 225.44.122.168.in-addr.arpa. domain name pointer comm595-0344-225.bu.edu [3600] 226.44.122.168.in-addr.arpa. domain name pointer comm595-0344-226.bu.edu [3600] 227.44.122.168.in-addr.arpa. domain name pointer comm595-0344-227.bu.edu [3600] 228.44.122.168.in-addr.arpa. domain name pointer comm595-0344-228.bu.edu [3600] 229.44.122.168.in-addr.arpa. domain name pointer comm595-0344-229.bu.edu [3600] 230.44.122.168.in-addr.arpa. domain name pointer comm595-0344-230.bu.edu [3600] 231.44.122.168.in-addr.arpa. domain name pointer comm595-0344-231.bu.edu [3600] 232.44.122.168.in-addr.arpa. domain name pointer comm595-0344-232.bu.edu [3600] 233.44.122.168.in-addr.arpa. domain name pointer comm595-0344-233.bu.edu [3600] 234.44.122.168.in-addr.arpa. domain name pointer comm595-0344-234.bu.edu [3600] 235.44.122.168.in-addr.arpa. domain name pointer comm595-0344-235.bu.edu [3600] 236.44.122.168.in-addr.arpa. domain name pointer comm595-0344-236.bu.edu [3600] 237.44.122.168.in-addr.arpa. domain name pointer comm595-0344-237.bu.edu [3600] 238.44.122.168.in-addr.arpa. domain name pointer comm595-0344-238.bu.edu [3600] 239.44.122.168.in-addr.arpa. domain name pointer comm595-0344-239.bu.edu [3600] 240.44.122.168.in-addr.arpa. domain name pointer comm595-0344-240.bu.edu [3600] 241.44.122.168.in-addr.arpa. domain name pointer smgpodium326.bu.edu [3600] 242.44.122.168.in-addr.arpa. domain name pointer smgpodium312.bu.edu [3600] 243.44.122.168.in-addr.arpa. domain name pointer smgpodium310.bu.edu [0] 244.44.122.168.in-addr.arpa.: domain name does not exist [0] 245.44.122.168.in-addr.arpa.: domain name does not exist [0] 246.44.122.168.in-addr.arpa.: domain name does not exist [0] 247.44.122.168.in-addr.arpa.: domain name does not exist [0] 248.44.122.168.in-addr.arpa.: domain name does not exist [0] 249.44.122.168.in-addr.arpa.: domain name does not exist [0] 250.44.122.168.in-addr.arpa.: domain name does not exist [0] 251.44.122.168.in-addr.arpa.: domain name does not exist [0] 252.44.122.168.in-addr.arpa.: domain name does not exist [0] 253.44.122.168.in-addr.arpa.: domain name does not exist [0] 254.44.122.168.in-addr.arpa.: domain name does not exist [0] 255.44.122.168.in-addr.arpa.: domain name does not exist