3098 X(delegation)s3377 X(.)s2256 X3231 Y2400 X(Lame)s2578 X(delegations)s2909 X(are)s3017 X(serious)s3232 X(problems)s3480 X(.)s3545 X(At)s3638 X(the)s2256 X3304 Y(very)s2399 X(least,)s2564 X(they)s2703 X(cause)s2876 X(the)s2982 X(DNS)s3139 X(to)s3215 X(become)s3447 X(much)s3619 X(less)s2256 X3377 Y(ef\256cient)s2512 X(since)s2686 X(query)s2873 X(packets)s3110 X(will)s3251 X(be)s3350 X(sent)s3494 X(to)s3583 X(hosts)s2256 X3450 Y(which)s2447 X(are)s2557 X(either)s2738 X(not)s2851 X(running)s3085 X(a)s3142 X(nameserver)s3477 X(at)s3553 X(all,)s3665 X(or)s2256 X3523 Y(will)s2387 X(be)s2476 X(sent)s2610 X(to)s2688 X(nameservers)s3049 X(which)s3239 X(are)s3348 X(not)s3460 X(authorita-)s2256 X3596 Y(tive)s2383 X(for)s2486 X(a)s2542 X(domain)s2742 X(.)s2806 X(In)s2886 X(either)s3064 X(case,)s3222 X(the)s3329 X(query)s3505 X(will)s3635 X(not)s2256 X3669 Y(be)s2343 X(answered,)s2636 X(and)s2757 X(the)s2864 X(sender)s3063 X(will)s3193 X(have)s3344 X(to)s3421 X(try)s3520 X(another)s2256 X3742 Y(nameserver)s2564 X(.)s2649 X(In)s2750 X(a)s2826 X(more)s3009 X(serious)s3244 X(case,)s3423 X(all)s3537 X(of)s3638 X(the)s2256 X3815 Y(nameservers)s2612 X(listed)s2780 X(for)s2879 X(a)s2932 X(domain)s3155 X(will)s3283 X(be)s3369 X(lame)s3523 X(delega-)s2256 X3888 Y(tions,)s2426 X(and)s2544 X(no)s2632 X(queries)s2847 X(can)s2962 X(be)s3047 X(answered!)s3365 X(Interestingly,)s2256 X3961 Y(a)s2310 X(site)s2428 X(can)s2545 X(be)s2632 X(the)s2739 X(victim)s2936 X(of)s3016 X(a)s3071 X(serious)s3285 X(lame)s3441 X(delegation)s2256 X4034 Y(such)s2404 X(as)s2485 X(this)s2607 X(without)s2836 X(even)s2987 X(being)s3160 X(aware)s3345 X(of)s3425 X(it)s3488 X(IF)s3572 X(all)s3665 X(of)s2256 X4107 Y(the)s2367 X(resolvers)s2638 X(on)s2704 X(-site)s2850 X(are)s2962 X(con\256gured)s3276 X(to)s3358 X(query)s3539 X(a)s3599 X(non)s3698 X(-)s2256 X4180 Y(lame)s2414 X(server,)s2621 X(yet)s2730 X(the)s2839 X(servers)s3055 X(listed)s3228 X(for)s3332 X(that)s3460 X(site)s3581 X(at)s3656 X(its)s2256 X4253 Y(parent)s2462 X(domain)s2701 X(are)s2823 X(all)s2931 X(lame)s3062 X(.)s3141 X(Unfortunately,)s3572 X(many)s2256 X4326 Y(excellent)s2535 X(examples)s2823 X(of)s2913 X(this)s3045 X(exist)s3207 X(even)s3368 X(today)s3551 X(in)s3638 X(the)s2256 X4399 Yf.B 9 Z(IN)s2322 X(-ADDR)s2514 X(.ARPA)s2737 Xf.R 10 Z(namespace)s3031 X(.)s3112 X(Here)s3284 X(the)s3409 X(scenario)s3675 X(is)s2256 X4472 Y(that)s2420 X(a)s2513 X(site)s2670 X(lists)s2842 X(no)s2971 X(nameservers)s3368 X(for)s3508 X(its)s3634 Xf.B 9 Z(IN)s3700 X(-)s2256 X4545 Y(ADDR)s2428 X(.ARPA)s2642 Xf.R 10 Z(domains\(s\))s2972 X(in)s3058 X(the)s3174 X(root)s3315 X(servers)s3538 X(due)s3668 X(to)s2256 X4618 Y(ignorance)s2554 X(or)s2644 X(oversight,)s2944 X(but)s3064 X(their)s3221 X(local)s3386 X(nameservers)s2256 X4691 Y(do)s2349 X(indeed)s2554 X(serve)s2722 X(their)s2872 Xf.B 9 Z(IN)s2938 X(-ADDR)s3130 X(.ARPA)s3339 Xf.R 10 Z(domain)s3539 X(.)s3606 X(And)s2256 X4764 Y(so,)s2385 X(local)s2569 X(queries)s2815 X(all)s2936 X(work)s3124 X(since)s3314 X(the)s3448 X(packet)s3675 X(is)s600 X4967 Yf.B 10 Z(1992)s754 X(LISA)s931 X(VI)s1027 X(\261)s1082 X(October)s1338 X(19)s1404 X(-23,)s1531 X(1992)s1685 X(\261)s1740 X(Long)s1909 X(Beach,)s2122 X(CA)s3621 X(127)s5280 Ypagebot%%Page: 128 2pagetopstdencoding /NTimes-Bold /Times-Bold RE/f.B /NTimes-Bold findfont def f.B 10 Z360 X215 Y(Dealing)s601 X(with)s749 X(Lame)s934 X(Delegations)s360 X448 Ystdencoding /NTimes-Roman /Times-Roman RE/f.R /NTimes-Roman findfont def f.R 10 Z(coincidentally)s795 X(going)s1002 X(to)s1110 X(a)s1196 X(nameserver)s1560 X(which)s1779 X(is)s360 X521 Y(authoritative)s723 X(for)s824 X(that)s949 Xf.B 9 Z(IN)s1015 X(-ADDR)s1207 X(.ARPA)s1411 Xf.R 10 Z(domain,)s1651 X(yet)s1756 X(all)s360 X594 Y(non)s459 X(-local)s654 X(queries)s889 X(on)s998 X(that)s1142 Xf.B 9 Z(IN)s1208 X(-ADDR)s1400 X(.ARPA)s1624 Xf.R 10 Z(domain)s360 X667 Y(fail)s473 X(since)s634 X(there)s791 X(are)s896 X(no)s985 X(nameservers)s1341 X(for)s1440 X(it)s1500 X(listed)s1668 X(in)s1742 X(the)s360 X740 Y(root)s489 X(servers)s678 X(.)s360 X867 Y907 Xf.B 10 Z(The)s1040 X(Solution)s360 X976 Y504 Xf.R 10 Z(Don)s651 X(Lewis,)s865 X(one)s994 X(of)s1082 X(the)s1197 X(few)s1330 X(people)s1541 X(across)s1742 X(the)s360 X1049 Y(Internet)s598 X(contributing)s954 X(bug)s1083 X(\256xes)s1239 X(and)s1364 X(enhancements)s1772 X(to)s360 X1122 Y(BIND,)s569 X(released)s819 X(a)s879 X(patch)s1054 X(which)s1247 X(detects)s1465 X(lame)s1627 X(delega-)s360 X1195 Y(tions)s490 X(.)s565 X(A)s649 X(lame)s815 X(delegation)s1129 X(is)s1209 X(detected)s1468 X(when)s1647 Xstdencoding /NTimes-Italic /Times-Italic RE/f.I /NTimes-Italic findfont def f.I 10 Z(named)s360 X1268 Yf.R 10 Z(forwards)s626 X(a)s686 X(query)s867 X(to)s949 X(a)s1010 X(nameserver)s1349 X(which)s1543 X(was)s1678 X(listed)s360 X1341 Y(as)s453 X(an)s553 X(authoritative)s929 X(server,)s1146 X(but)s1268 X(the)s1387 X(response)s1657 X(is)s1739 X(not)s360 X1414 Y(marked)s583 X(as)s663 X(authoritative)s1002 X(.)s1065 X(A)s1137 X(lame)s1292 X(delegation)s1595 X(causes)s1794 X(a)s360 X1487 Y(message)s613 X(like)s739 X(this)s861 X(to)s938 X(appear)s1141 X(in)s1218 X(the)s1325 X(appropriate)s1654 X(syslog)s360 X1560 Y(log:)sstdencoding /NCourier /Courier RE/f.CW /NCourier findfont def 360 X1662 Y408 Xf.CW 10 Z(Jun)s568 X(23)s688 X(11:06:42)s1048 X(totalrecall)s360 X1735 Y408 X(named[104]:)s888 X(Lame)s1088 X(delegation)s1528 X(to)s360 X1808 Y408 X(`nadn)s608 X(.NAVY)s808 X(.MIL')s1048 X(received)s1408 X(from)s360 X1881 Y408 X(26)s488 X(.7)s568 X(.0)s648 X(.102)s848 X(\(purported)s1288 X(server)s1568 X(for)s360 X1954 Y408 X(`NADN)s608 X(.NAVY)s808 X(.MIL'\))s1088 X(on)s1208 X(query)s1448 X(on)s1568 X(name)s360 X2027 Y408 X([ward)s608 X(.nadn)s808 X(.navy)s1008 X(.mil])s360 X2150 Y504 Xf.R 10 Z(In)s597 X(this)s732 X(example,)s1014 X(the)s1134 X(namserver)s1450 X(on)s1554 X(totalrecall)s360 X2223 Y(came)s539 X(across)s743 X(this)s877 X(lame)s1044 X(delegation)s1359 X(when)s1539 X(it)s1613 X(tried)s1772 X(to)s360 X2296 Y(resolve)s584 X(the)s697 X(name)s874 Xf.B 9 Z(WARD)s1063 X(.NADN)s1250 X(.NAVY)s1437 X(.MIL)s1572 Xf.R 10 Z(.)s1643 X(At)s1742 X(the)s360 X2369 Y(time)s550 X(of)s675 X(this)s842 X(writing,)s1121 X(there)s1324 X(are)s1475 X(three)s1678 X(listed)s360 X2442 Y(nameservers)s720 X(for)s823 X(the)s931 Xf.B 9 Z(NADN)s1103 X(.NAVY)s1290 X(.MIL)s1452 Xf.R 10 Z(domains)s1705 X(with)s360 X2515 Y(the)s529 X(names:)s805 Xf.B 9 Z(NADN1)s1007 X(.NADN)s1194 X(.NAVY)s1381 X(.MIL)s1602 Xf.R 10 Z(\(address)s360 X2588 Y(131)s459 X(.121)s575 X(.1)s625 X(.1\),)s786 Xf.B 9 Z(USNA)s948 X(.USNA)s1125 X(.NAVY)s1312 X(.MIL)s1520 Xf.R 10 Z(\(26)s1608 X(.7)s1658 X(.0)s1708 X(.102)s360 X2661 Y(and)s536 X(128)s635 X(.56)s718 X(.1)s768 X(.1\),)s937 X(and)s1113 Xf.B 9 Z(NADN2)s1315 X(.NADN)s1502 X(.NAVY)s1689 X(.MIL)s360 X2734 Yf.R 10 Z(\(131)s481 X(.121)s597 X(.1)s647 X(.2\))s719 X(.)s805 X(In)s907 X(this)s1052 X(case,)s1233 X(our)s1369 X(nameserver)s1725 X(for-)s360 X2807 Y(warded)s580 X(the)s686 X(query)s861 X(on)s951 X(the)s1057 X(name)s1226 Xf.B 9 Z(WARD)s1415 X(.NADN)s1602 X(.NAVY)s1789 X(.-)s2016 X448 Y(MIL)s2178 Xf.R 10 Z(to)s2272 X(a)s2344 X(nameserver)s2694 X(it)s2774 X(was)s2920 X(led)s3044 X(to)s3139 X(believe)s3376 X(was)s2016 X521 Y(authoritative)s2384 X(for)s2490 Xf.B 9 Z(NADN)s2662 X(.NAVY)s2849 X(.MIL)sf.R 10 Z(,)s3030 X(yet)s3141 X(in)s3222 X(this)s3347 X(case,)s2016 X594 Y(that)s2139 X(nameserver)s2469 X(replied)s2677 X(with)s2818 X(non)s2917 X(-authoritative)s3300 X(data)s3412 X(.)s2016 X688 Y2160 X(Since)s2344 X(we)s2457 X(started)s2672 X(running)s2914 X(a)s2980 X(version)s3212 X(of)s3303 Xf.I 10 Z(named)s2016 X761 Yf.R 10 Z(with)s2169 X(this)s2299 X(patch,)s2494 X(we)s2605 X(found)s2792 X(that)s2926 X(we)s3037 X(discovered)s3359 X(hun-)s2016 X834 Y(dreds)s2184 X(of)s2263 X(lame)s2418 X(delegations)s2748 X(each)s2896 X(month)s3066 X(.)s3130 X(Furthermore,)s2016 X907 Y(although)s2283 X(some)s2458 X(lame)s2623 X(delegations)s2962 X(were)s3126 X(indeed)s3337 X(prob-)s2016 X980 Y(lems)s2169 X(with)s2314 X(a)s2370 X(domain)s2596 X(nameserver)s2931 X(at)s3007 X(the)s3116 X(University)s3425 X(of)s2016 X1053 Y(Michigan,)s2362 X(most)s2565 X(were)s2768 X(problems)s3089 X(with)s3280 X(domain)s2016 X1126 Y(nameservers)s2372 X(located)s2588 X(elsewhere)s2878 X(in)s2952 X(the)s3056 X(Internet)s3264 X(.)s2016 X1220 Y2160 X(At)s2256 X(\256rst)s2389 X(we)s2496 X(ignored)s2728 X(the)s2840 X(non)s2939 X(-local)s3122 X(lame)s3283 X(delega-)s2016 X1293 Y(tion)s2154 X(messages)s2440 X(and)s2569 X(simply)s2784 X(used)s2939 X(a)s3002 X(tool)s3139 X(like)s3273 Xf.I 10 Z(grep)s3428 Xf.R 10 Z(to)s2016 X1366 Y(extract)s2234 X(the)s2351 X(lame)s2517 X(delegations)s2857 X(that)s2994 X(were)s3160 X(local)s3291 X(.)s3366 X(Yet,)s2016 X1439 Y(even)s2170 X(this)s2295 X(proved)s2507 X(to)s2587 X(be)s2678 X(less)s2807 X(effective)s3070 X(than)s3213 X(we)s3318 X(hoped)s2016 X1512 Y(since)s2192 X(many)s2378 X(of)s2471 X(the)s2591 X(lame)s2760 X(delegations)s3103 X(proved)s3326 X(to)s3417 X(be)s2016 X1585 Y(transient)s2292 X(problems,)s2602 X(and)s2743 X(there)s2922 X(was)s3070 X(little)s3239 X(sense)s3428 X(in)s2016 X1658 Y(alerting)s2258 X(a)s2325 X(hostmaster)s2652 X(to)s2741 X(a)s2808 X(problem)s3067 X(that)s3206 X(no)s3310 X(longer)s2016 X1731 Y(existed)s2206 X(.)s2281 X(We)s2410 X(decided)s2653 X(to)s2740 X(build)s2912 X(a)s2977 X(tool)s3116 X(which)s3314 X(would)s2016 X1804 Y(screen)s2222 X(out)s2342 X(as)s2433 X(many)s2616 X(transient)s2882 X(or)s2972 X(spurious)s3233 X(errors)s3424 X(as)s2016 X1877 Y(possible,)s2016 X2023 Y(and)s2147 X(would)s2349 X(then)s2500 X(automatically)s2902 X(alert)s3058 X(the)s3176 X(appropriate)s2016 X2096 Y(hostmaster)s2328 X(via)s2432 X(e)s2462 X(-mail)s2604 X(.)s2016 X2223 Y2617 Xf.B 10 Z(The)s2750 X(Tool)s2016 X2332 Y2160 Xf.R 10 Z(We)s2276 X(wrote)s2451 X(a)s2504 X(small)s2673 X(shell)s2823 X(script)s2995 X(which)s3181 X(we)s3283 X(run)s3395 X(out)s2016 X2405 Y(of)s2114 Xf.I 10 Z(cron)s2279 Xf.R 10 Z(once)s2448 X(per)s2576 X(week)s2717 X(.)s2799 X(The)s2946 X(script)s3138 X(is)s3226 X(relatively)s2016 X2478 Y(short,)s2205 X(and)s2340 X(we)s2457 X(thought)s2699 X(the)s2820 X(best)s2967 X(way)s3117 X(to)s3209 X(present)s3442 X(it)s2016 X2551 Y(would)s2212 X(be)s2304 X(to)s2385 X(simple)s2593 X(include)s2819 X(an)s2911 X(annotated)s3200 X(version)s3425 X(of)s2016 X2624 Y(it)s2081 X(here)s2196 X(.)s2262 X(It)s2330 X(is)s2402 X(also)s2537 X(available)s2807 X(via)s2916 X(anonymous)s3249 X(ftp)s3351 X(from)s2016 X2697 Y(terminator)s2295 X(.cc)s2372 X(.umich)s2556 X(.edu)s2669 X(.)s2782 X(It)s2897 X(can)s3064 X(be)s3201 X(found)s3428 X(in)s2016 X2770 Y(/dns/lamers)s2325 X(.sh)s2401 X(.)s360 X2970 Y1766 Xf.B 10 Z(The)s1899 X(Script)s360 X3136 Y504 Xf.R 10 Z(The)s632 X(\256rst)s760 X(part)s888 X(of)s967 X(the)s1073 X(script)s1246 X(sets)s1371 X(up)s1461 X(our)s1573 X(path,)s1729 X(identi\256es)s1999 X(the)s2106 X(location)s2347 X(of)s2427 X(the)s2534 X(log)s2644 X(\256le,)s2772 X(identi\256es)s3043 X(the)s3150 X(\256le)s3261 X(contain-)s360 X3209 Y(ing)s470 X(the)s577 X(lame)s732 X(delegation)s1035 X(message)s1286 X(we)s1388 X(send)s1534 X(to)s1610 X(people,)s1829 X(and)s1949 X(identi\256es)s2219 X(some)s2384 X(temp)s2542 X(\256les)s2654 X(.)s2717 X(Notice)s2920 X(that)s3045 X(some)s3210 X(temp)s3368 X(\256les)s360 X3282 Y(are)s468 X(located)s688 X(on)s780 X(/usr/tmp)s1029 X(rather)s1211 X(than)s1352 X(/tmp)s1475 X(.)s1540 X(Some)s1718 X(of)s1799 X(these)s1964 X(\256les)s2103 X(can)s2223 X(get)s2332 X(big)s2444 X(as)s2527 X(the)s2636 X(script)s2812 X(runs,)s2970 X(and)s3093 X(we)s3198 X(found)s3379 X(that)s360 X3355 Y(we)s460 X(would)s648 X(\256ll)s745 X(up)s833 X(/tmp)s978 X(\(which)s1185 X(is)s1252 X(on)s1340 X(the)s1444 X(/)s1485 X(partition)s1734 X(on)s1822 X(our)s1932 X(machines\))s2207 X(.)s360 X3457 Y408 Xf.CW 10 Z(#!/bin/sh)s360 X3530 Y408 X(PATH=:/bin:/usr)s1008 X(/bin:/usr/ucb:/)s1608 X(usr/local/bin)s360 X3603 Y408 X(LOGFILE=/usr/sp)s1008 X(ool/log/named)s360 X3676 Y408 X(MAILMSG=/usr/tm)s1008 X(p/mailmsg$$)s360 X3749 Y408 X(LAMERS=/usr/tmp)s1008 X(/lamers$$)s360 X3822 Y408 X(MSGFILE=/usr/lo)s1008 X(cal/bin/lamer)s1528 X(-message)s