1 URL 2 IP addresses?

[mktck]

Recently I am having issues connecting from my site to a URL. The connection to it keeps dropping. While doing tracerts, i realised the URL resolves to 2 different IP addresses. One time resolves to 210.x.x.24 and some other time it resolves to 202.x.x.229. How is this possible?

Here is the trace when I am able to connect.

Tracing route to

http://www.(URL).com

[210.x.x.24]
over a maximum of 30 hops:

1 <1 ms <1 ms <1 ms 10.10.11.1
2 1 ms 1 ms 1 ms 63.x.x.130
3 3 ms 2 ms 2 ms S-edge.ISP.net[63.x.x.45]
4 3 ms 2 ms 2 ms S-core.ISP.net[65.x.x.17]
5 33 ms 33 ms 34 ms H-core.ISP.net[65.x.x.58]
6 33 ms 33 ms 33 ms H-brdr-01.ISP.net [65.x.x.38]
7 35 ms 35 ms 35 ms P.ISP2.Net [202.x.x.180]
8 35 ms 34 ms 35 ms 210.x.x.57
9 35 ms 34 ms 35 ms 210.x.x.62
10 35 ms 35 ms 35 ms 210.x.x.4
11 40 ms 39 ms 36 ms 210.x.x.126
12 37 ms 36 ms 36 ms 210.x.x.1

It hops to 12 and the rest are behind a firewall, but I am able to access the URL from my browser.

If the connection is down, it hops to 6 and everything after that is timed out. And the URL is inaccessible.

As you can see, ISP.net is my ISP while ISP2.net is the destination URL's ISP. Both ISPs claimed that the circuit is working fine, but I still get disconnected from the URL every few hours.

Is it my Cisco C1700 router's problem? IP CEF and IP VERIFY UNICAST RESERVER ROUTE is set.

 

[mktck]

Here is the Running Config from my C1700 edited.
#show run
Building configuration...

Current configuration : 1510 bytes
!
version 12.3
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname cisco
!
boot-start-marker
boot-end-marker
!
enable password *****
!
memory-size iomem 25
no aaa new-model
ip subnet-zero
!
!
!
!
ip tcp window-size 65535
no ip domain lookup
ip cef
!
!
!
controller E1 0
channel-group 0 unframed
!
controller E1 1
channel-group 1 unframed
!
!
interface FastEthernet0
ip address 63.x.x.130 255.255.255.224
speed auto
full-duplex
!
interface Serial0:0
ip address 63.x.x.46 255.255.255.252
ip verify unicast reverse-path
max-reserved-bandwidth 50
custom-queue-list 1
traffic-shape rate 1000000 250000 250000 1000
!
interface Serial1:1
no ip address
!
ip classless
ip route 0.0.0.0 0.0.0.0 63.x.x.45
no ip http server
!
!
queue-list 1 protocol ip 1 udp domain
queue-list 1 protocol ip 2 tcp smtp
queue-list 1 protocol ip 3 tcp www
queue-list 1 default 4
queue-list 1 queue 3 byte-count 1000
queue-list 1 queue 4 byte-count 500
snmp-server community cisco RO
snmp-server enable traps tty
!
control-plane
!
!
line con 0
line aux 0
line vty 0 4
password *****
login
!
end

 

[unclerico]

the first thing that comes to mind is DNS round-robin

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[burtsbees]

Like Google and Yahoo.

/

tim@tim-laptop ~ $ sudo apt-get install windows
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Couldn't find package windows...Thank Goodness!

 

[mktck]

What on earth is a DNS round robin? haha...never encounter this before. Please enlighten me more while i google the term as well. Any advise for my circuit?

 

[mahlad29]

just a simple load balancing algorithim, One request here one request here, back and forth.

20 yrs old, working towards my CCNP. Looking for a new job
02472

 

[mahlad29]

Connection to host lost.

C:\Users\mike>nslookup google.com
Server: vnsc-bak.sys.gtei.net
Address: 4.2.2.2

Non-authoritative answer:
Name: google.com
Addresses: 74.125.67.100
74.125.45.100
74.125.53.100

Look google has 3, from which each leads to a farm, and behind each farm they use rfc1918 addr. and load balance back there. Thats just there homepage.

20 yrs old, working towards my CCNP. Looking for a new job
02472

 

[mktck]

Did another trace today. I think my ISP side did some changes. Take a look and any advise or opinions are appreciated.

Previous trace at hop 6 and 7
6 32 ms 35 ms 34 ms H-brdr-01.ISP.net [65.x.x.38]
7 34 ms 38 ms 34 ms P.ISP2.net [202.x.x.180]

Today's trace at hop 6 and 7
6 33 ms 33 ms 33 ms H-brdr-01.ISP.net [65.x.x.34]
7 35 ms 35 ms 35 ms U.ISP2.net [202.x.x.56]

Noticed that the H-brdr-01 changed IP, and hop 7 is a different IP also. Could it be my ISP finally realised they boggled up?

 

[mktck]

Should I use

IP Host

http://www.(URL).com

202.x.x.229

so it won't rely on the round robin? any advantage to do this?

 

[StaplesMan]

This post seems old but no one really answered your question, so I thought some education may help...

The problem you have is someplace on the internet there is a router that is down or some routing issue. As you access the website some times it get's an IP address that you can access other times it get's the ip address that takes the route over the network that does not work.

The problem is out of your hands. Could be your ISPs or the backbone or the web hosting routers or there server.

The Round Robin configuration is on your DNS server. But turning it off will cause you to get the same IP over and over again and it could be the one that does not work.

The command you noted above would work correctly if your router was setup as the DNS server. But you must have an in-house dns server (windows server any chance) and because of this that command would not help. I can tell this because you are missing the needed dns server commands on your router such as:
ip domain round-robin
ip name-server 4.2.2.2
ip dns server



Ways to fix the problem
1. Wait until it's fixed (the best)
2. Modify your host file on your PC this would fix it for your computer only. Simply add the domain and IP address in the list. c:\windows\system32\drivers\etc\hosts
3. Modify your DNS server with a custom host and A Record.

The drawback with option 2 or 3 is if they change servers to a different IP address you will be unable to access it again, if you forgot to remove the settings.

Hope all is working now any way. Hope this info was useful!



CCNA, A+, HP Certified Professional