为什么我ping百度的时候，却显示正在ping www.a.shifen.com

这是dns解析过程中，www.baidu.com作为cname记录（相当于别名），在dns服务器中配置了www.baidu.com到www.a.shifen.com的映射记录。而www.a.shifen.com是作为A（address）记录，映射到了真实的IP信息。

只是个别名而已，要想看dns解析过程，使用dig命令查看即可。
C:\Users\Think>dig www.baidu.com +trace

; <<>> DiG 9.11.3 <<>> www.baidu.com +trace
;; global options: +cmd
. 18918 IN NS f.root-servers.net.
. 18918 IN NS e.root-servers.net.
. 18918 IN NS c.root-servers.net.
. 18918 IN NS l.root-servers.net.
. 18918 IN NS j.root-servers.net.
. 18918 IN NS k.root-servers.net.
. 18918 IN NS i.root-servers.net.
. 18918 IN NS b.root-servers.net.
. 18918 IN NS g.root-servers.net.
. 18918 IN NS a.root-servers.net.
. 18918 IN NS m.root-servers.net.
. 18918 IN NS d.root-servers.net.
. 18918 IN NS h.root-servers.net.
;; Received 751 bytes from 202.103.24.68#53(202.103.24.68) in 22 ms

com. 172800 IN NS l.gtld-servers.net.
com. 172800 IN NS b.gtld-servers.net.
com. 172800 IN NS c.gtld-servers.net.
com. 172800 IN NS d.gtld-servers.net.
com. 172800 IN NS e.gtld-servers.net.
com. 172800 IN NS f.gtld-servers.net.
com. 172800 IN NS g.gtld-servers.net.
com. 172800 IN NS a.gtld-servers.net.
com. 172800 IN NS h.gtld-servers.net.
com. 172800 IN NS i.gtld-servers.net.
com. 172800 IN NS j.gtld-servers.net.
com. 172800 IN NS k.gtld-servers.net.
com. 172800 IN NS m.gtld-servers.net.
com. 86400 IN DS 30909 8 2 E2D3C916F6DEEAC73294E8268FB5885044A833FC5459588F4A9184CF C41A5766
com. 86400 IN RRSIG DS 8 1 86400 20220403220000 20220321210000 9799 . LDN2V0zbN/iwib7cJaANigbhWu4ABoIE8I7Bcs7n/AeCiW6qaUt8YOd2 U0dNRAA3SaJmyVNGXpVWX7PyEEUd3xQSn22jegSFhFzHEn/eijF8bvng ANmyRFkeMa5mDrpg4zBFY1+vEoPBHshS1cI3a2KmectRBvjeid874rjc BsiD2CQ/otbqsxA1nKXtO01pJFxaKCML8JJZAOv3xC1xrw09csONy9j9 FAJRLe9i/IqLAocsuspqRB85W0rQWEsSGq9/glP8BQS9Bj1aQAhhNR+8 M4C2daXcTx0XtgcqrvosYA+TOqvkM6aslGZ3++lYLlQ/iDuMKj9856cM 1bO26A==
;; Received 1173 bytes from 192.5.5.241#53(f.root-servers.net) in 226 ms

baidu.com. 172800 IN NS ns2.baidu.com.
baidu.com. 172800 IN NS ns3.baidu.com.
baidu.com. 172800 IN NS ns4.baidu.com.
baidu.com. 172800 IN NS ns1.baidu.com.
baidu.com. 172800 IN NS ns7.baidu.com.
CK0POJMG874LJREF7EFN8430QVIT8BSM.com. 86400 IN NSEC3 1 1 0 - CK0Q1GIN43N1ARRC9OSM6QPQR81H5M9A NS SOA RRSIG DNSKEY NSEC3PARAM
CK0POJMG874LJREF7EFN8430QVIT8BSM.com. 86400 IN RRSIG NSEC3 8 2 86400 20220328042357 20220321031357 38535 com. iij4WqjI3nDDdk7006EdZVoo2Eg9fk9Zj9pR96ZGij8jyUdoEzdKidbB rpcDziHFvfjaTkb69qYkOvPC9FOLFBGi85RI0Wk0LrrU15R3ha77nD5p mEq/YwoBgbGOd3QKxPIisGyXMaTfLo8K2UVknVSP2pBU2jBTYDfatZh7 HtXcH6RS55ve/km6NlKpX2MjSDEmU0kXcQJWt/Fg9HM5fw==
HPVU6NQB275TGI2CDHPDMVDOJC9LNG86.com. 86400 IN NSEC3 1 1 0 - HPVV8SARM2LDLRBTVC5EP1CUB1EF7LOP NS DS RRSIG
HPVU6NQB275TGI2CDHPDMVDOJC9LNG86.com. 86400 IN RRSIG NSEC3 8 2 86400 20220325043210 20220318032210 38535 com. QEKRHiJImPLB0dT3szg6oC72TQY06afVTUIsPFTg921pKVf1thXun8V9 zosBswcv0iGBSVc4+I5BTmbpRPK41mQk55o2kq7clRmgEgb/+oAuS/9e xSTsA1f94NsCRXqQjeqdWOKCj1JmZa/UMQG30pu7leDko44/vFYNJBkf fEdlEZSSgm9Or5Oh9yFYunMpoSr+Hp332MxmAn9zOOlyrQ==
;; Received 817 bytes from 192.54.112.30#53(h.gtld-servers.net) in 263 ms

www.baidu.com. 1200 IN CNAME www.a.shifen.com.
a.shifen.com. 1200 IN NS ns1.a.shifen.com.
a.shifen.com. 1200 IN NS ns2.a.shifen.com.
a.shifen.com. 1200 IN NS ns4.a.shifen.com.
a.shifen.com. 1200 IN NS ns3.a.shifen.com.
a.shifen.com. 1200 IN NS ns5.a.shifen.com.
;; Received 295 bytes from 112.80.248.64#53(ns3.baidu.com) in 22 ms

这个确实是正常的。
另外一种情况是hosts文件被修改，显然你的不是。

恩！
这个是对百度网址加的外壳！
以免被攻击的！
这个纯属网络安全的范畴...
望采纳！