PIx 501 and DNS

Hi all,

I have a client who has a static config for internet access, for some of the clients there is intermitant access to the internet, do I have to specify the DNS servers of ISP?  here is the current config:

PIX Version 6.3(5)
interface ethernet0 auto
interface ethernet1 100full
nameif ethernet0 outside security0
nameif ethernet1 inside security100
enable password lJtNxIBCFSIPDh0I encrypted
passwd 2KFQnbNIdI.2KYOU encrypted
hostname neba
domain-name neba.com
fixup protocol dns maximum-length 512
fixup protocol ftp 21
fixup protocol h323 h225 1720
fixup protocol h323 ras 1718-1719
fixup protocol http 80
fixup protocol rsh 514
fixup protocol rtsp 554
fixup protocol sip 5060
fixup protocol sip udp 5060
fixup protocol skinny 2000
no fixup protocol smtp 25
fixup protocol sqlnet 1521
fixup protocol tftp 69
names
access-list outside_in permit tcp any interface outside eq smtp
access-list inside_outbound_nat0_acl permit ip any 172.27.20.32 255.255.255.224
access-list outside_cryptomap_dyn_20 permit ip any 172.27.20.32 255.255.255.224
pager lines 24
mtu outside 1500
mtu inside 1500
ip address outside 80.4.178.3 255.255.255.192
ip address inside 172.27.20.254 255.255.252.0
ip audit info action alarm
ip audit attack action alarm
ip local pool nb1 172.27.20.40-172.27.20.50
pdm location 172.27.20.2 255.255.255.255 inside
pdm logging informational 100
pdm history enable
arp timeout 14400
global (outside) 1 interface
nat (inside) 0 access-list inside_outbound_nat0_acl
nat (inside) 1 0.0.0.0 0.0.0.0 0 0
static (inside,outside) tcp interface smtp 172.27.20.2 smtp netmask 255.255.255.255 0 0
access-group outside_in in interface outside
route outside 0.0.0.0 0.0.0.0 80.4.168.62 1
timeout xlate 0:05:00
timeout conn 1:00:00 half-closed 0:10:00 udp 0:02:00 rpc 0:10:00 h225 1:00:00
timeout h323 0:05:00 mgcp 0:05:00 sip 0:30:00 sip_media 0:02:00
timeout sip-disconnect 0:02:00 sip-invite 0:03:00
timeout uauth 0:05:00 absolute
aaa-server TACACS+ protocol tacacs+
aaa-server TACACS+ max-failed-attempts 3
aaa-server TACACS+ deadtime 10
aaa-server RADIUS protocol radius
aaa-server RADIUS max-failed-attempts 3
aaa-server RADIUS deadtime 10
aaa-server LOCAL protocol local
http server enable
http 172.27.20.0 255.255.252.0 inside
no snmp-server location
no snmp-server contact
snmp-server community public
no snmp-server enable traps
floodguard enable
sysopt connection permit-ipsec
crypto ipsec transform-set ESP-3DES-MD5 esp-3des esp-md5-hmac
crypto dynamic-map outside_dyn_map 20 match address outside_cryptomap_dyn_20
crypto dynamic-map outside_dyn_map 20 set transform-set ESP-3DES-MD5
crypto map outside_map 65535 ipsec-isakmp dynamic outside_dyn_map
crypto map outside_map interface outside
isakmp enable outside
isakmp policy 20 authentication pre-share
isakmp policy 20 encryption 3des
isakmp policy 20 hash md5
isakmp policy 20 group 2
isakmp policy 20 lifetime 86400
telnet timeout 5
ssh timeout 5
console timeout 0
dhcpd lease 3600
dhcpd ping_timeout 750
dhcpd auto_config outside
terminal width 80
Cryptochecksum:c94a153a39490c4062274a86853f3571
: end
[OK]