Why is dhclient + systemd-resolved restarting frequently?












0















I'm running an ubuntu server in aws on VERSION="18.10 (Cosmic Cuttlefish)"



We've been having intermittent dns resolution issues, and while looking into that I've seen that every 20 minutes or so I'm seeing the following in syslog



Mar 19 00:17:03 localhost dhclient[815]: DHCPREQUEST of 172.31.26.85 on eth0 to 172.31.16.1 port 67 (xid=0x7d329bb3)
Mar 19 00:17:03 localhost dhclient[815]: DHCPACK of 172.31.26.85 from 172.31.16.1
Mar 19 00:17:03 localhost systemd[1]: Stopping Network Name Resolution...
Mar 19 00:17:03 localhost systemd[1]: Stopped Network Name Resolution.
Mar 19 00:17:03 localhost systemd[1]: Starting Network Name Resolution...
Mar 19 00:17:04 localhost dhclient[815]: bound to 172.31.26.85 -- renewal in 1747 seconds.


It seems every time dhclient goes through a renewal process it causes systemd-resolved to restart, which momentarily makes dns resolution not work. So if some process was running at that time, the resolution may fail.



I'm not really sure where to begin on this. Is it normal for dhclient to cause systemd-resolved to restart so frequently? What's the right solution to this issue? Should I force dhclient to renew much less frequently, does that have some negative impact? Any other suggestions?










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  • 1





    "renewal in 1747 seconds" suggests maybe the network's DHCP server is configured to offer ~30 minute lease durations?

    – steeldriver
    1 hour ago
















0















I'm running an ubuntu server in aws on VERSION="18.10 (Cosmic Cuttlefish)"



We've been having intermittent dns resolution issues, and while looking into that I've seen that every 20 minutes or so I'm seeing the following in syslog



Mar 19 00:17:03 localhost dhclient[815]: DHCPREQUEST of 172.31.26.85 on eth0 to 172.31.16.1 port 67 (xid=0x7d329bb3)
Mar 19 00:17:03 localhost dhclient[815]: DHCPACK of 172.31.26.85 from 172.31.16.1
Mar 19 00:17:03 localhost systemd[1]: Stopping Network Name Resolution...
Mar 19 00:17:03 localhost systemd[1]: Stopped Network Name Resolution.
Mar 19 00:17:03 localhost systemd[1]: Starting Network Name Resolution...
Mar 19 00:17:04 localhost dhclient[815]: bound to 172.31.26.85 -- renewal in 1747 seconds.


It seems every time dhclient goes through a renewal process it causes systemd-resolved to restart, which momentarily makes dns resolution not work. So if some process was running at that time, the resolution may fail.



I'm not really sure where to begin on this. Is it normal for dhclient to cause systemd-resolved to restart so frequently? What's the right solution to this issue? Should I force dhclient to renew much less frequently, does that have some negative impact? Any other suggestions?










share|improve this question







New contributor




user3005200 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
















  • 1





    "renewal in 1747 seconds" suggests maybe the network's DHCP server is configured to offer ~30 minute lease durations?

    – steeldriver
    1 hour ago














0












0








0








I'm running an ubuntu server in aws on VERSION="18.10 (Cosmic Cuttlefish)"



We've been having intermittent dns resolution issues, and while looking into that I've seen that every 20 minutes or so I'm seeing the following in syslog



Mar 19 00:17:03 localhost dhclient[815]: DHCPREQUEST of 172.31.26.85 on eth0 to 172.31.16.1 port 67 (xid=0x7d329bb3)
Mar 19 00:17:03 localhost dhclient[815]: DHCPACK of 172.31.26.85 from 172.31.16.1
Mar 19 00:17:03 localhost systemd[1]: Stopping Network Name Resolution...
Mar 19 00:17:03 localhost systemd[1]: Stopped Network Name Resolution.
Mar 19 00:17:03 localhost systemd[1]: Starting Network Name Resolution...
Mar 19 00:17:04 localhost dhclient[815]: bound to 172.31.26.85 -- renewal in 1747 seconds.


It seems every time dhclient goes through a renewal process it causes systemd-resolved to restart, which momentarily makes dns resolution not work. So if some process was running at that time, the resolution may fail.



I'm not really sure where to begin on this. Is it normal for dhclient to cause systemd-resolved to restart so frequently? What's the right solution to this issue? Should I force dhclient to renew much less frequently, does that have some negative impact? Any other suggestions?










share|improve this question







New contributor




user3005200 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.












I'm running an ubuntu server in aws on VERSION="18.10 (Cosmic Cuttlefish)"



We've been having intermittent dns resolution issues, and while looking into that I've seen that every 20 minutes or so I'm seeing the following in syslog



Mar 19 00:17:03 localhost dhclient[815]: DHCPREQUEST of 172.31.26.85 on eth0 to 172.31.16.1 port 67 (xid=0x7d329bb3)
Mar 19 00:17:03 localhost dhclient[815]: DHCPACK of 172.31.26.85 from 172.31.16.1
Mar 19 00:17:03 localhost systemd[1]: Stopping Network Name Resolution...
Mar 19 00:17:03 localhost systemd[1]: Stopped Network Name Resolution.
Mar 19 00:17:03 localhost systemd[1]: Starting Network Name Resolution...
Mar 19 00:17:04 localhost dhclient[815]: bound to 172.31.26.85 -- renewal in 1747 seconds.


It seems every time dhclient goes through a renewal process it causes systemd-resolved to restart, which momentarily makes dns resolution not work. So if some process was running at that time, the resolution may fail.



I'm not really sure where to begin on this. Is it normal for dhclient to cause systemd-resolved to restart so frequently? What's the right solution to this issue? Should I force dhclient to renew much less frequently, does that have some negative impact? Any other suggestions?







networking dns display-resolution dhcp systemd-resolved






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  • 1





    "renewal in 1747 seconds" suggests maybe the network's DHCP server is configured to offer ~30 minute lease durations?

    – steeldriver
    1 hour ago














  • 1





    "renewal in 1747 seconds" suggests maybe the network's DHCP server is configured to offer ~30 minute lease durations?

    – steeldriver
    1 hour ago








1




1





"renewal in 1747 seconds" suggests maybe the network's DHCP server is configured to offer ~30 minute lease durations?

– steeldriver
1 hour ago





"renewal in 1747 seconds" suggests maybe the network's DHCP server is configured to offer ~30 minute lease durations?

– steeldriver
1 hour ago










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