hostname

hostname of host can be configured by editing /etc/hostname file.

static IP address

By default, hosts are configured to obtain IP address from DHCP Server. Configuration is stored in /etc/network/interfaces file.

auto eth0
iface eth0 inet dhcp

Replace above as follows so that IP address 10.0.3.10 is statically assigned for interface eth0.

auto eth0
iface eth0 inet static
address 10.0.3.10
network 10.0.3.0
netmask 255.255.255.0
broadcast 10.0.3.255
gateway 10.0.3.1

resolver

As advertised in it, /etc/resolv.conf file will be overwritten upon system reboot.

# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN

You need to configure IP addresses of DNS servers and search domain in /etc/network/interfaces file as well.

dns-search example.org
dns-nameservers 10.0.3.10 10.0.3.1 8.8.8.8

Resolver will generates such lines as follows in /etc/resolv.conf.

nameserver 10.0.3.10
nameserver 10.0.3.1
nameserver 8.8.8.8
search example.org

Following entry is a good reference.