Debian Issue with DHCP client on interface with static IP

Initial state

Eth1 switched to static IP instead DHCP by config:

/etc/network/interfaces

source /etc/network/interfaces.d/*

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
allow-hotplug eth0
iface eth0 inet dhcp


allow-hotplug eth1
#face ens19 inet dhcp
iface eth1 inet static
    address 192.168.99.10/24

Execute:

ifdown eth1
ifup eth1

The process dhcpclient for Eth1 still running:

# ps auxf | grep dhcp
root         438  0.0  0.1   5868  3544 ?        Ss   Sep20   0:00 dhclient -4 -v -i -pf /run/dhclient.eth1.pid -lf /var/lib/dhcp/dhclient.eth1.leases -I -df /var/lib/dhcp/dhclient6.eth1.leases eth1
root         445  0.0  0.1   5872  3480 ?        Ss   Sep20   0:00 dhclient -4 -v -i -pf /run/dhclient.eth0.pid -lf /var/lib/dhcp/dhclient.eth0.leases -I -df /var/lib/dhcp/dhclient6.eth0.leases eth0

As result? the new value of DNS name server has been set in /etc/resolv.conf

Solution

Kill dhcpclient process for eth1