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Multiple Servers - Same Hostname

Posted on 2014-04-22
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Last Modified: 2014-04-25
Hi

I was wondering if I ping some of the internet servers e.g. relay.lusovps.com I get reply from different IPs at different times (see below ping).

Can someone explain what type of DNS entries I need to create to do this?

-bash-4.1# ping relay.lusovps.com
PING relay.lusovps.com (37.247.50.113) 56(84) bytes of data.
64 bytes from relay.lusovps.com (37.247.50.113): icmp_seq=1 ttl=51 time=126 ms
64 bytes from relay.lusovps.com (37.247.50.113): icmp_seq=2 ttl=50 time=118 ms
^C
--- relay.lusovps.com ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1450ms
rtt min/avg/max/mdev = 118.267/122.244/126.222/3.992 ms

-bash-4.1# ping relay.lusovps.com
PING relay.lusovps.com (192.249.61.189) 56(84) bytes of data.
64 bytes from relay.lusovps.com (192.249.61.189): icmp_seq=1 ttl=54 time=83.8 ms
64 bytes from relay.lusovps.com (192.249.61.189): icmp_seq=2 ttl=54 time=75.2 ms
^C
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Question by:sysautomation
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4 Comments
 
LVL 8

Expert Comment

by:nader alkahtani
ID: 40014458
If it is Windows servers you should read this solution from its reference http://support.microsoft.com/kb/981953/en-us
----------------------------------------------------------------OR
the first replay from (public IP)
the second replay is from (internal IP)
did you ping from PC it self ? if yes go to following :
------------------------------------------------------------------OR
Try flush DNS that in Windows is equal to ipconfig/flushdns

http://www.cyberciti.biz/faq/rhel-debian-ubuntu-flush-clear-dns-cache/

then test
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LVL 17

Expert Comment

by:Sajid Shaik M
ID: 40014533
it's cause of DNS propogation

check this link to understand the DNS

https://www.whatsmydns.net/#A/relay.lusovps.com

In order to understand DNS propagation, you must first understand a little about how DNS works. When you set up your website with us, we create a Master DNS record in our Domain Name Servers. When you change the name servers, your domain registrar (the company you paid for the honor of owning your domain name) points your domain to our DNS server as being the master authority of your domain.

When any outside source wants to know how to find your website, they first go to the registration database to find out who the DNS authority is for your website. Then they visit our DNS servers to find out what the IP Address is for your domain name, and from there your audience can now view your website.

The problem with this whole scheme is that in order to speed up the rate at which their customers can view the internet, each Internet Server Provider caches their DNS records. This means that they make their own copy of the master records, and read from them locally instead of looking them up on the Internet each time someone wants view a website. This actually speeds up web surfing quite a bit, by (1) speeding up the return time it takes for a web browser to request a domain lookup and get an answer, and (2) actually reducing the amount of traffic on the web therefore giving it the ability to work faster.

The downside to this caching scenario and what makes it take so long for your website to be visible to everyone, is that each company or ISP that caches DNS records only updates them every few days. This is not any kind of standard, and they can set this time anywhere from a few hours to several days. The slow updating of the servers cache is called propagation, since your websites DNS information is now being propagated across all DNS servers on the web. When this is finally complete, everyone can now visit your new website. Being that the cache time is different for all servers, as mentioned above, it can take anywhere from 24 to 72 hours for DNS changes to be totally in effect.

all the best
0
 
LVL 19

Accepted Solution

by:
alextoft earned 900 total points
ID: 40014794
This question has nothing to do with DNS propagation. Simply that the host you're trying to ping has multiple A records. It's entirely legal to have 1 host resolve to several different IP addresses.

host -v relay.lusovps.com

Trying "relay.lusovps.com"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 45576
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;relay.lusovps.com.            IN      A

;; ANSWER SECTION:
relay.lusovps.com.      21599      IN      A      37.247.50.113
relay.lusovps.com.      21599      IN      A      37.247.52.149
relay.lusovps.com.      21599      IN      A      192.249.61.189
0
 
LVL 13

Assisted Solution

by:Sandy
Sandy earned 600 total points
ID: 40014855
This is called CDN computing where single app/service/cluster is being configured in such a way to balance the load and provide redundancy.

CDN provides nearest hop to end-user to serve fast and with better speed. You can check here..

Natively this was used to manage the load among multiple nodes using DNS Round-Robin load balancing and in the above scenario it seems me that only.

http://en.wikipedia.org/wiki/Content_delivery_network

TY/SA
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