Fedora 25 primeiro tempo de consulta de DNS

Question

Não sei por onde começar, mas recentemente minhas pesquisas de DNS ficaram extremamente lentas, sempre em 5 segundos. Depois de executar strace ping -c 1 google.com , observei que a primeira pesquisa de DNS sempre atinge o tempo limite:

poll([{fd=5, events=POLLIN}], 1, 5000)  = 1 ([{fd=5, revents=POLLIN}])
ioctl(5, FIONREAD, [56])                = 0
recvfrom(5,         "a210
poll([{fd=5, events=POLLIN}], 1, 5000)  = 1 ([{fd=5, revents=POLLIN}])
ioctl(5, FIONREAD, [56])                = 0
recvfrom(5,         "a210%pre%%pre%%pre%%pre%%pre%%pre%googlecom%pre%%pre%%pre%0\f%pre%"...,     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, "16%pre%%pre%%pre%%pre%%pre%%pre%%pre%%pre%googlecom%pre%%pre%%pre%", 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,     "1610%pre%%pre%%pre%%pre%%pre%%pre%googlecom%pre%%pre%%pre%0\f%pre%"...,     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, "a2%pre%%pre%%pre%%pre%%pre%%pre%%pre%%pre%googlecom%pre%%pre%%pre%", 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,     "a210%pre%%pre%%pre%%pre%%pre%%pre%googlecom%pre%%pre%%pre%0\f%pre%"...,     65536, 0, {sa_family=AF_INET, sin_port=htons(53),     sin_addr=inet_addr("8.8.8.8")}, [28->16]) = 56
close(5)          
%pre%%pre%%pre%%pre%%pre%googlecom%pre%%pre%%pre%0\f%pre%"...,     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, "16%pre%%pre%%pre%%pre%%pre%%pre%%pre%%pre%googlecom%pre%%pre%%pre%", 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,     "1610%pre%%pre%%pre%%pre%%pre%%pre%googlecom%pre%%pre%%pre%0\f%pre%"...,     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, "a2%pre%%pre%%pre%%pre%%pre%%pre%%pre%%pre%googlecom%pre%%pre%%pre%", 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,     "a210%pre%%pre%%pre%%pre%%pre%%pre%googlecom%pre%%pre%%pre%0\f%pre%"...,     65536, 0, {sa_family=AF_INET, sin_port=htons(53),     sin_addr=inet_addr("8.8.8.8")}, [28->16]) = 56
close(5)          

Estou lendo o strace corretamente? O que poderia estar acontecendo aqui?

Executando o Fedora 25.

    

Answer 1

Adicionar options single-request-reopen ao meu /etc/resolv.conf resolveu o problema!