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Helpful
4
Replies

Can't ping isp DNS or Internet

tonymlee18
Level 1
Level 1

Hi

For some reason I can't ping the dns or browse to the Internet.

I have a cisco 851W

I have DSL and setup to dhcp.

When I do a show ip int 4 it shows a ip address picked up for my ISP. So  I know I can get a IP address but I can't ping the DNS which is

72.235.80.12 and 72.235.80.4

Thanks.


!
version 12.4
no service pad
service tcp-keepalives-in
service tcp-keepalives-out
service timestamps debug datetime msec localtime show-timezone
service timestamps log datetime msec localtime show-timezone
service password-encryption
service sequence-numbers
!
hostname smithrouter
!
boot-start-marker
boot-end-marker
!
logging buffered 51200
logging console critical
enable secret 5 cisco
!
no aaa new-model
!
dot11 syslog
!
dot11 ssid tgsmdinc
authentication open
!
no ip source-route
no ip dhcp use vrf connected
ip dhcp excluded-address 192.168.1.1
!
ip dhcp pool ccp-pool1
import all
network 192.168.1.0 255.255.255.0
dns-server 72.235.80.12 72.235.80.4
default-router 192.168.1.1
!
!
ip cef
no ip bootp server
ip domain name smith.local
ip name-server 72.235.80.12
ip name-server 72.235.80.4
!
!
!
username smith privilege 15 secret 5 cisco
!
!
archive
log config
hidekeys
!
!
ip tcp synwait-time 10
ip ssh time-out 60
ip ssh authentication-retries 2
!
bridge irb
!
!
interface FastEthernet0
!
interface FastEthernet1
!
interface FastEthernet2
!
interface FastEthernet3
!
interface FastEthernet4
description $FW_OUTSIDE$$ES_WAN$
ip address dhcp client-id FastEthernet4
no ip redirects
no ip unreachables
no ip proxy-arp
ip nat outside
ip virtual-reassembly
ip route-cache flow
duplex auto
speed auto
!
interface Dot11Radio0
no ip address
!
ssid tgsmdinc
!
speed basic-1.0 basic-2.0 basic-5.5 6.0 9.0 basic-11.0 12.0 18.0 24.0 36.0 48.0 54.0
station-role root
bridge-group 1
bridge-group 1 subscriber-loop-control
bridge-group 1 spanning-disabled
bridge-group 1 block-unknown-source
no bridge-group 1 source-learning
no bridge-group 1 unicast-flooding
!
interface Vlan1
description $ETH-SW-LAUNCH$$INTF-INFO-HWIC 4ESW$$FW_INSIDE$
no ip address
ip tcp adjust-mss 1452
bridge-group 1
!
interface BVI1
description $ES_LAN$$FW_INSIDE$
ip address 192.168.1.1 255.255.255.0
ip nat inside
ip virtual-reassembly
ip tcp adjust-mss 1412
!
ip forward-protocol nd
ip route 0.0.0.0 0.0.0.0 FastEthernet4
!
ip http server
ip http access-class 23
ip http authentication local
ip http secure-server
ip http timeout-policy idle 60 life 86400 requests 10000
ip nat inside source list 1 interface FastEthernet4 overload
!
logging trap debugging
access-list 1 remark INSIDE_IF=BVI1
access-list 1 remark CCP_ACL Category=2
access-list 1 permit 192.168.1.0 0.0.0.255
no cdp run
!
control-plane
!
bridge 1 protocol ieee
bridge 1 route ip
!
line con 0
login local
no modem enable
transport output telnet
line aux 0
login local
transport output telnet
line vty 0 4
privilege level 15
login local
transport input telnet ssh
!
scheduler max-task-time 5000
scheduler allocate 4000 1000
scheduler interval 500
end

1 Accepted Solution

Accepted Solutions

Hello Tony,

Can you remove the default route you have in the configuration?

no ip route 0.0.0.0 0.0.0.0 FastEthernet4

Then, bounce the FastEthernet 4 interface. That should allow the ISP to set

the default route.

Hope this helps.

Regards,

NT

View solution in original post

4 Replies 4

kyukim
Cisco Employee
Cisco Employee

Hi, Tony.

If you can't ping your ISP DNS but you can ping ISP default GW, this means your ISP DNS has a problem.

I do see this kind of problem from my ISP too.

Try to use public well known DNS server, like 4.2.2.2.

I usually configure my dhcp server to use one of my ISP dns and secondary as 4.2.2.2

ip name-server 72.235.80.12
ip name-server 4.2.2.2.

Try to ping 4.2.2.2 from your router. If you can't ping, then your ISP has a problem.

KK

Hi KK

I still can't get out to the Internet.

If I use my other router I can ping both DNS and go to the Internet fine.

I just have this problem with the cisco router.

Any other suggestions?

thanks

btw cant ping 4.2.2.2 either but I can ping the gateway fine.

if i'm on my linksys router I can ping 4.2.2.2 and 72.235.80.12 just fine but not on the cisco router.

Hello Tony,

Can you remove the default route you have in the configuration?

no ip route 0.0.0.0 0.0.0.0 FastEthernet4

Then, bounce the FastEthernet 4 interface. That should allow the ISP to set

the default route.

Hope this helps.

Regards,

NT

wow! thanks! that worked!!!

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