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Fedora 25 首次 DNS 查找超时

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Fedora 25 首次 DNS 查找超时

不知道从哪里开始，但最近我的 DNS 查找变得非常慢，总是 5 秒。运行后strace ping -c 1 google.com我注意到第一次 DNS 查找总是超时：

poll([{fd=5, events=POLLIN}], 1, 5000)  = 1 ([{fd=5, revents=POLLIN}])
ioctl(5, FIONREAD, [56])                = 0
recvfrom(5,         "a\322\201\200\0\1\0\1\0\0\0\0\6google\3com\0\0\34\0\1\300\f\0\34"...,     2048, 0, {sa_family=AF_INET, sin_port=htons(53),     sin_addr=inet_addr("8.8.8.8")}, [28->16]) = 56

>>>
>>> Timeout happens here
>>> poll([{fd=5, events=POLLIN}], 1, 4960
>>> )  = 0 (Timeout)
>>>

poll([{fd=5, events=POLLOUT}], 1, 0)    = 1 ([{fd=5,     revents=POLLOUT}])
sendto(5, "\361\226\1\0\0\1\0\0\0\0\0\0\6google\3com\0\0\1\0\1", 28,     MSG_NOSIGNAL, NULL, 0) = 28
poll([{fd=5, events=POLLIN}], 1, 5000)  = 1 ([{fd=5, revents=POLLIN}])
ioctl(5, FIONREAD, [44])                = 0
recvfrom(5,     "\361\226\201\200\0\1\0\1\0\0\0\0\6google\3com\0\0\1\0\1\300\f\0\1"...,     2048, 0, {sa_family=AF_INET, sin_port=htons(53),     sin_addr=inet_addr("8.8.8.8")}, [28->16]) = 44
poll([{fd=5, events=POLLOUT}], 1, 4958) = 1 ([{fd=5,     revents=POLLOUT}])
sendto(5, "a\322\1\0\0\1\0\0\0\0\0\0\6google\3com\0\0\34\0\1", 28,     MSG_NOSIGNAL, NULL, 0) = 28
poll([{fd=5, events=POLLIN}], 1, 4958)  = 1 ([{fd=5, revents=POLLIN}])
ioctl(5, FIONREAD, [56])                = 0
recvfrom(5,     "a\322\201\200\0\1\0\1\0\0\0\0\6google\3com\0\0\34\0\1\300\f\0\34"...,     65536, 0, {sa_family=AF_INET, sin_port=htons(53),     sin_addr=inet_addr("8.8.8.8")}, [28->16]) = 56
close(5)

我读得strace正确吗？这里可能发生什么？

运行 Fedora 25。

答案1

添加options single-request-reopen到我/etc/resolv.conf解决的问题！

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