connecting to the internet even with the DNS server down

@optimystix-4yMPKC • Oct 25, 2024

Oct 25, 2024

1.2K

while commenting on another #-Link-Snipped-#I read about the Akamai hacking incident and it was then that a question struck me. The question is that, when we type a web address on the address bar of our browser (say we typed #-Link-Snipped-#), the DNS server looks up the DNS table for the appropriate numerical address(IP?) of the website and then routes it towards the destination. Now, suppose the DNS servers were down, would it be possible to connect directly by using the known IP address of the website?
I mean instead of typing <a href="https://www.google.com" target="_blank" rel="nofollow noopener noreferrer">Google</a>, what if we typed //209.85.153.104/ ?
will it still connect with the DNS servers down or does it still need access to them ?

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Manish Goyal

@manish-r2Hoep • Jun 22, 2010

I think yes,by making entries in Host file in windows.
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Kaustubh Katdare

@thebigk • Jun 22, 2010

Well, if I understood your question correctly - yes you can connect to any web server directly. Alternatively, you could make relevant entry in the hosts file of your system to point to the relevant destination.
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Manish Goyal

@manish-r2Hoep • Jun 22, 2010

One more thing to add How about configuring your own Local DNS server?
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optimystix

@optimystix-4yMPKC • Jun 22, 2010

The_Big_K
Well, if I understood your question correctly - yes you can connect to any web server directly. Alternatively, you could make relevant entry in the hosts file of your system to point to the relevant destination.
so you mean to say that the DNS servers are useful only if one types the domain name of the target website in text and that the DNS has no role to play when we connect to a website directly through its ip address ?
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Kaustubh Katdare

@thebigk • Jun 22, 2010

optimystix
so you mean to say that the DNS servers are useful only if one types the domain name of the target website in text and that the DNS has no role to play when we connect to a website directly through its ip address ?
Well, I'm not an expert on this, but from what I've learned is that DNS servers are meant to give the domains (IP addresses) a meaningful name. There might be other uses too; but I"m not aware of them. You can bypass a DNS by configuring hosts file locally and you won't notice a difference!

It may make a difference to the way you access website if you're connecting with IP and not using DNS. If your website has the addresses hard-coded; then they may result into error (from my observation).
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optimystix

@optimystix-4yMPKC • Jun 22, 2010

goyal420
One more thing to add How about configuring your own Local DNS server?
well, there are DNS servers that ISPs use by default but one can also set their own preferred DNS server address (such as Open DNS) by modifying the TCP/IP setting in the network properties.

But is there any way to totally avoid using a DNS server? That is to bypass and avoid the DNS used by web servers or ISPs?
Obviously it will give error when trying to connect to any website but is it possible to arrive at such a situation?
I want to experiment on something regarding this, that is why am asking.
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durga ch

@durga-TpX3gO • Jun 22, 2010

I tried connecting using an IP address instead of a URL
1.Google.com.au --- check-- I could connect when I type the IP address
2.unsw.edu.au -- check
3.timesofindia.com -- fail --I could not connect
4.crazyengineers.com --- fail I could not connect
5.blogspot.com --checked -redirected to google
6.wordpress.com -- check

One thing what I noticed to be common between 3,4 is they belong to Class D IP addresses. I don't know why I could not connect, though My pings were all good.

Are you sure, all the websites would be inaccessible? Because I believe DNS server is actually a group of DB servers right? So if one goes down i believe we should still be to access the web pages from other DNS servers.
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Manish Goyal

@manish-r2Hoep • Jun 22, 2010

optimystix
well, there are DNS servers that ISPs use by default but one can also set their own preferred DNS server address (such as Open DNS) by modifying the TCP/IP setting in the network properties.

But is there any way to totally avoid using a DNS server? That is to bypass and avoid the DNS used by web servers or ISPs?
Obviously it will give error when trying to connect to any website but is it possible to arrive at such a situation?
I want to experiment on something regarding this, that is why am asking.
DNS servers are made for our ease .It is actually a database(actually a distribute database) that provides mapping between domain names and ip addresses

I think there will be no problem if DNS servers down .

correct me if i am wrong
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optimystix

@optimystix-4yMPKC • Jun 22, 2010

durga
I tried connecting using an IP address instead of a URL
1.Google.com.au --- check-- I could connect when I type the IP address
2.unsw.edu.au -- check
3.timesofindia.com -- fail --I could not connect
4.crazyengineers.com --- fail I could not connect
5.blogspot.com --checked -redirected to google
6.wordpress.com -- check

One thing what I noticed to be common between 3,4 is they belong to Class D IP addresses. I don't know why I could not connect, though My pings were all good.

Are you sure, all the websites would be inaccessible? Because I believe DNS server is actually a group of DB servers right? So if one goes down i believe we should still be to access the web pages from other DNS servers.
yes durga, the pings you sent above has got nothing to do with 'DNS off' thing as it still would be accessing the DNS to make the connection in case if you typed the web address. The internet would become really inaccessible if all DNS servers could be turned off.

As you correctly mentioned, I too could not connect to CE site when I tried to connect through the ip address. Is it because the server is behind some protection such as a proxy ? 'Cos the site pings when connected through the domain name but not through the ip address.

does biggie know the reason why(about the CE site not connecting through ip) ?
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optimystix

@optimystix-4yMPKC • Jun 22, 2010

goyal420
DNS servers are made for our ease .It is actually a database(actually a distribute database) that provides mapping between domain names and ip addresses

I think there will be no problem if DNS servers down .

correct me if i am wrong
i know about the DNS but what I want to know is whether there is a way to avoid visiting one?

by setting preferred DNS on tcp/ip properties, one can make their preferred DNS server to be accessed instead of the default one and if preferred is not used, then it accesses the default one used by the isp.

is it possible to not use any DNS servers at all by some manual process? am not saying about turning down DNS servers, but bypassing it on just my computer. is it possible ? anyone ?
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durga ch

@durga-TpX3gO • Jun 22, 2010

@ Opti

Are you saying you want to remember all the Ip addresses of various the web pages :-| and completely dodge DNS? or you say you have a mechanism where even though you type in a site name, you still end up connecting with some means to map the address name to the IP??
Tell me know exactly are you thinking ?
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MaRo

@maro-Ce3knx • Jun 22, 2010

It has to be a dedicated IP address to work, usually there's several websites on the same server have the same IP, this is internally managed by server to know the intended website, but externally the world sees all the websites on that server with the same IP.
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optimystix

@optimystix-4yMPKC • Jun 22, 2010

MaRo
It has to be a dedicated IP address to work, usually there's several websites on the same server have the same IP, this is internally managed by server to know the intended website, but externally the world sees all the websites on that server with the same IP.
yes MaRo, I too think this is the reason for not being able to connect to sites such as CE. I had faced same prob a few months back when I was using WireShark to check the incoming and outgoing packets from a particular online server.

@durga
I just wanted to completely dodge the DNS as u say. Not that I want to remember all the ip addresses and use them (I would certainly be mad enough to do so 😛) but I wanted to experiment something on it. Some nice idea for experimentation struck me last night but am unable to recall it this morning 😔. Not even a hint of what it was!

Never mind though, will share it up here as soon as I get a clue. But is it possible Durga, to completely bypass the DNS structure ?
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vik001ind

@vik001ind-rOaCSy • Jun 22, 2010

I don't think so!
There is lots of ip forwarding taking place while accessing the internet which will be barred when you enter only the ip, thats why websites are not accessible by entering the ip only. DNS server plays some role in providing a path (packet switched) to the packets from server to client. Enter >tracert <ip address> to see the path taken by your packets.
How are you going to dodge all those servers. If you dodge, you will have no connectivity at all.
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Ashraf HZ

@Ash • Jun 23, 2010

MaRo
It has to be a dedicated IP address to work, usually there's several websites on the same server have the same IP, this is internally managed by server to know the intended website, but externally the world sees all the websites on that server with the same IP.
Yep, this is correct. Virtual name servers are used to host multiple websites on the same IPs. In these cases, you'll still need to use DNS to access the required info from the name servers.

Companies or organizations that have their own servers do need dedicated IPs. In fact, the google.com domain has multiple IPs for redundancy and load balancing. Accessing each IP directly would usually get you to one of their countless routers.

In addition, how you access the IP is important.. accessing the IP address with the http protocol (via browser) will attempt to access using port 80 (in most cases).. which may or may not be restricted.

Its pretty much hit or miss when in comes to DNS usage. Depends on where the website is hosted on as well as the firewall rules.
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