Dynamic DNS with ADSL Routers

[3wsparky]

Hi People , have a question about using my isps dns servers for my web browsing requests

have a cisco 837 and 1700 both giving the same issues so i think its just conf command missing or something

if i ping a url add

http://www.google.co.uk

i get a response when doing it from my router
RTR-ADSL#ping

http://www.google.co.uk

Translating "

http://www.google.co.uk"...domain

server (212.135.1.36) [OK]

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 216.239.59.99, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 24/28/36 ms

but if i run it from my desktop pc it wont resolve
i have tried removing the dns-servers from the dhcp conf and ipconfig /renew but it wont dns proxy what am i doing wrong here ?



Building configuration...

Current configuration : 3872 bytes
!
version 12.3
no service pad
service timestamps debug datetime msec
service timestamps log datetime msec
service password-encryption
!
hostname RTR-ADSL
!
logging buffered informational
!

ip subnet-zero
ip dhcp database data
ip dhcp excluded-address 192.168.1.1
ip dhcp excluded-address 192.168.1.3
!
ip dhcp pool CLIENT
import all
network 192.168.1.0 255.255.255.0
default-router 192.168.1.1
dns-server 212.135.1.36 195.40.1.36
lease 0 2
!
!
ip inspect name myfw cuseeme timeout 3600
ip inspect name myfw ftp timeout 3600
ip inspect name myfw rcmd timeout 3600
ip inspect name myfw realaudio timeout 3600
ip inspect name myfw smtp timeout 3600
ip inspect name myfw tftp timeout 30
ip inspect name myfw udp timeout 15
ip inspect name myfw tcp timeout 3600
ip inspect name myfw h323 timeout 3600
no aaa new-model
password encryption aes
!
!
!
!
!
!
!
interface Ethernet0
ip address 192.168.1.1 255.255.255.0
ip nat inside
no ip mroute-cache
hold-queue 100 out
!
interface ATM0
no ip address
no ip mroute-cache
atm vc-per-vp 64
no atm ilmi-keepalive
pvc 0/38
encapsulation aal5mux ppp dialer
dialer pool-member 1
!
dsl operating-mode auto
!
interface Dialer1
ip address negotiated
ip access-group 111 in
ip nat outside
ip inspect myfw out
encapsulation ppp
dialer pool 1
dialer-group 1
ppp authentication chap pap callin
ppp chap hostname .co.uk
ppp chap password 7 151D
ppp pap sent-username .co.uk password 7 151D
30
ppp ipcp dns request accept
ppp ipcp wins request accept
hold-queue 224 in
!
ip nat inside source list 102 interface Dialer1 overload
ip nat inside source static tcp 192.168.1.3 5800 interface Dialer1 5800
ip classless
ip route 0.0.0.0 0.0.0.0 Dialer1
ip http server
ip http secure-server
!
access-list 23 permit 192.168.1.0 0.0.0.255
access-list 102 permit ip 192.168.1.0 0.0.0.255 any
access-list 111 permit icmp any any administratively-prohibited
access-list 111 permit icmp any any echo
access-list 111 permit icmp any any echo-reply
access-list 111 permit icmp any any packet-too-big
access-list 111 permit icmp any any time-exceeded
access-list 111 permit icmp any any traceroute
access-list 111 permit icmp any any unreachable
access-list 111 permit udp any eq bootps any eq bootpc
access-list 111 permit udp any eq bootps any eq bootps
access-list 111 permit udp any eq domain any
access-list 111 permit esp any any
access-list 111 permit udp any any eq isakmp
access-list 111 permit udp any any eq 10000
access-list 111 permit tcp any any eq 1723
access-list 111 permit tcp any any eq 139
access-list 111 permit udp any any eq netbios-ns
access-list 111 permit udp any any eq netbios-dgm
access-list 111 permit gre any any
access-list 111 deny ip any any log
dialer-list 1 protocol ip permit

!
line con 0
login local
no modem enable
line aux 0
line vty 0 4
access-class 23 in
exec-timeout 120 0
login local
length 0
!
scheduler max-task-time 5000
!
end

RTR-ADSL#

 

[sirlollypop]

I would definitly remove the DNS servers from the DHCP config and also remove the IP inspect config. I have had it do some funny things to DNS packets where it does some kind of deep inspect and repalces the dns server address!! The other thing I can see is under the dialer interface you have 2 commands:

ppp ipcp dns request accept
ppp ipcp wins request accept

when I set up dsl using cisco I just have:

ppp ipcp dns request
ppp ipcp wins request

try it and let me know I will try is out.

 

[sirlollypop]

One thing I forgot after removing the DNs config from the router do a DHCP refresh on the PC then and ipconfig /all to see what the PC thinks it DNS servers are.

 

[burtsbees]

I had the same issue with my 837, until I did this...
router>en
router#conf t
router(config)#ip name-server xxx.xxx.xxx.xxx
router(config)#ip name-server xxx.xxx.xxx.xxx
you keep adding this command for each different dns server
This is what sends dns info to the nodes in the DHCP config.
Hope this helps.

Burt

 

[3wsparky]

i have changed the ipcp an all seems ok so far altho something is worrying me ,

from the router prompt i cant do a ping dns name if fails to resolve and the pc ipconfig /all has the two dns servers in there that where same as the static ones i suspect its not worked and is running on its previous lease shall have a closer look 2mo tho.

cheers sirlollypop

 

[burtsbees]

Try adding the ip name-server command.

Burt

 

[sirlollypop]

Some ISPs (BT to name one) change their DNS servers regularly so hard coding them will sometimes cause an issue and should be left to be dynamically assigned.

& it looks like you are using the GUI to config the router I have had trouble with that too so went back to conf t mode

 

[3wsparky]

out the box it had a gui on it , i just tweeked it but i dont use the gui , to many bright colours confuse me )

yes dynamic dns is the way foward for a trouble free router,
and as stands all seems ok so far still.

 

[burtsbees]

I see, sir lollypop. I did not know that some ISP's do that. Thanks for the info. And I agree, 3wsparky---bright colors confuse me as well. Ha ha. thanks.

Burt