???????????ping???????????TTL????ж??????????
???????????(TTL)??IP?????е????????????е?·??????????????????ж????IP?????????????????????????????????????????????????????????????IP????????????????????????????????磺?????·???п?????????IP??????????????????????????????????????????????????飬???????????????????????????????????????????????顣TTL???????????????????λ??IP?????????????8????????λ?????趨TTL????????????????????????????????????λ?????????????????????????鶪???????????·??????????????TTL?????????????TTL????????????????????鱻???????????????·???????????·???????????????????TTL ??????????????????0??·??????????????飬?????????ICMP??????????????????????
????UNIX ???? UNIX ?????? ICMP ???????? TTL ?????             255
????Compaq Tru64 5.0 ICMP ???????? TTL ?????                          64
????Windows NT/2K?????? ICMP ???????? TTL ?????              128
????Windows 95 ?????? ICMP ???????? TTL ?????                    32
???????ICMP???????????????￡?
????ECHO (Request (Type 8)?? Reply (Type 0))--???????
????Time Stamp (Request (Type 13)?? Reply (Type 14))--????????????
????Information (Request (Type 15)?? Reply (Type16))--???????????
????Address Mask (Request (Type 17)?? Reply (Type 18))--????????????????
????????????????????TTL?????????????????￡?
????Linux????TTL??64??255??
????Windows NT/2000/XP????TTL??128??
????Windows 98????TTL??32??
????UNIX??????TTL??255??
?????????????????Windows 2000????????TTL?????128??????????????255??????????????????????????Linux????UNIX???????????????Linux????UNIX????????Windows 2000?????????????????????????????????????????????????????????????????????????
????????????????
???????TTL????????????????????????????????“???→????”????“????”???????????“regedit”?????????????
????“???????”????????“HKEY_LOCAL_MACHINESystemCurrentControlSetServicesTcpip Parameters”?????“DefaultTTL”?????????????????“255”????????????????????ɡ?