root@raspberrypi:/etc/hostapd# service isc-dhcp-server restart
Job for isc-dhcp-server.service failed. See 'systemctl status isc-dhcp-server.se                                                                                        rvice' and 'journalctl -xn' for details.
root@raspberrypi:/etc/hostapd# systemctl status isc-dhcp-server.service
● isc-dhcp-server.service - LSB: DHCP server
   Loaded: loaded (/etc/init.d/isc-dhcp-server)
   Active: failed (Result: exit-code) since Fri 2016-12-09 15:26:01 UTC; 15s ago
  Process: 16641 ExecStart=/etc/init.d/isc-dhcp-server start (code=exited, statu                                                                                        s=1/FAILURE)

Dec 09 15:25:59 raspberrypi dhcpd[16650]:
Dec 09 15:25:59 raspberrypi dhcpd[16650]: No subnet declaration for wlan0 (1....
Dec 09 15:25:59 raspberrypi dhcpd[16650]: ** Ignoring requests on wlan0.  If...t
Dec 09 15:25:59 raspberrypi dhcpd[16650]: you want, please write a subnet de...n
Dec 09 15:25:59 raspberrypi dhcpd[16650]: in your dhcpd.conf file for the ne...t
Dec 09 15:26:01 raspberrypi isc-dhcp-server[16641]: Starting ISC DHCP server:...
Dec 09 15:26:01 raspberrypi isc-dhcp-server[16641]: failed!
Dec 09 15:26:01 raspberrypi systemd[1]: isc-dhcp-server.service: control pro...1
Dec 09 15:26:01 raspberrypi systemd[1]: Failed to start LSB: DHCP server.
Dec 09 15:26:01 raspberrypi systemd[1]: Unit isc-dhcp-server.service entered....
Hint: Some lines were ellipsized, use -l to show in full.
root@raspberrypi:/etc/hostapd# cat /etc/dhcp/dhcpd.conf
#
# Sample configuration file for ISC dhcpd for Debian
#
#

# The ddns-updates-style parameter controls whether or not the server will
# attempt to do a DNS update when a lease is confirmed. We default to the
# behavior of the version 2 packages ('none', since DHCP v2 didn't
# have support for DDNS.)
#ddns-update-style none;

# option definitions common to all supported networks...
#option domain-name "example.org";
#option domain-name-servers ns1.example.org, ns2.example.org;

default-lease-time 600;
max-lease-time 7200;

# If this DHCP server is the official DHCP server for the local
# network, the authoritative directive should be uncommented.
#authoritative;

# Use this to send dhcp log messages to a different log file (you also
# have to hack syslog.conf to complete the redirection).
#log-facility local7;

# No service will be given on this subnet, but declaring it helps the
# DHCP server to understand the network topology.

#subnet 10.152.187.0 netmask 255.255.255.0 {
#}

# This is a very basic subnet declaration.

#subnet 10.254.239.0 netmask 255.255.255.224 {
#  range 10.254.239.10 10.254.239.20;
#  option routers rtr-239-0-1.example.org, rtr-239-0-2.example.org;
#}

# This declaration allows BOOTP clients to get dynamic addresses,
# which we don't really recommend.

#subnet 10.254.239.32 netmask 255.255.255.224 {
#  range dynamic-bootp 10.254.239.40 10.254.239.60;
#  option broadcast-address 10.254.239.31;
#  option routers rtr-239-32-1.example.org;
#}

# A slightly different configuration for an internal subnet.
#subnet 10.5.5.0 netmask 255.255.255.224 {
#  range 10.5.5.26 10.5.5.30;
#  option domain-name-servers ns1.internal.example.org;
#  option domain-name "internal.example.org";
#  option routers 10.5.5.1;
#  option broadcast-address 10.5.5.31;
#  default-lease-time 600;
#  max-lease-time 7200;
#}

# Hosts which require special configuration options can be listed in
# host statements.   If no address is specified, the address will be
# allocated dynamically (if possible), but the host-specific information
# will still come from the host declaration.

#host passacaglia {
#  hardware ethernet 0:0:c0:5d:bd:95;
#  filename "vmunix.passacaglia";
#  server-name "toccata.fugue.com";
#}

# Fixed IP addresses can also be specified for hosts.   These addresses
# should not also be listed as being available for dynamic assignment.
# Hosts for which fixed IP addresses have been specified can boot using
# BOOTP or DHCP.   Hosts for which no fixed address is specified can only
# be booted with DHCP, unless there is an address range on the subnet
# to which a BOOTP client is connected which has the dynamic-bootp flag
# set.
#host fantasia {
#  hardware ethernet 08:00:07:26:c0:a5;
#  fixed-address fantasia.fugue.com;
#}

# You can declare a class of clients and then do address allocation
# based on that.   The example below shows a case where all clients
# in a certain class get addresses on the 10.17.224/24 subnet, and all
# other clients get addresses on the 10.0.29/24 subnet.

#class "foo" {
#  match if substring (option vendor-class-identifier, 0, 4) = "SUNW";
#}

#shared-network 224-29 {
#  subnet 10.17.224.0 netmask 255.255.255.0 {
#    option routers rtr-224.example.org;
#  }
#  subnet 10.0.29.0 netmask 255.255.255.0 {
#    option routers rtr-29.example.org;
#  }
#  pool {
#    allow members of "foo";
#    range 10.17.224.10 10.17.224.250;
#  }
#  pool {
#    deny members of "foo";
#    range 10.0.29.10 10.0.29.230;
#  }
#}
# If this DHCP server is the official DHCP server for the local
# network, the authoritative directive should be uncommented.
authoritative;

# No service will be given on this subnet, but declaring it helps the
# DHCP server to understand the network topology.

subnet 192.168.3.0 netmask 255.255.255.0 {
 range 192.168.3.2 192.168.3.30;
 option broadcast-address 192.168.255.255;
 option routers 192.168.3.1;
 option domain-name-servers 10.8.0.1;
}
root@raspberrypi:/etc/hostapd#