Forward all domain queries to new server

**Dylan** · Apr 28th 2017

Hi,

I would like to move my old server to a new server next monday. (server i-mscp version: 1.3.1)
After I move all domains etc, I would like to forward all DNS queries from old server to my new server's IP.

Why?
1. Some domain nameserver changes take a lot of time, so I would like to forward all DNS queries to new IP.
2. Some domain is not my handling, so my clients need some time to update their own domain's nameservers.

Is it possible somehow?

And other question:
Can I change the default TTL for all domain temporarly? (for faster IP update)

Thank you!

**kess** · Apr 30th 2017

On your old server run the following:

Code

sed -i 's/192.168.1.1/172.16.16.1/g' /var/cache/bind/*.db
sed -i 's/192.168.2.1/172.16.17.1/g' /var/cache/bind/*.db
service bind9 restart

Where:
- 192.168.1.1 is your primary OLD IP Address
- 192.168.2.1 is your secondary OLD IP Address
- 172.16.16.1 is your primary NEW IP Address
- 172.16.17.1 is your secondary NEW IP Address

So, all the DNS queries performed against your OLD server, will receive the new IP addresses as answers.

Hope it helps,
bye Kess.

**Nuxwin** · Apr 30th 2017

@kess

Hmm... That will not solve propagation issues. Those records can be cached on other DNS servers... Also, when changing something in a zone file, you must also update the serial You should really avoid giving such sed command

Quote from Dylan

Can I change the default TTL for all domain temporarly? (for faster IP update)

No, you cannot do that. TTL is also cached. changing it would have no impact on propagation time.

**kess** · Apr 30th 2017

@Nuxwin Yes i know, you are right.
In fact generally you change TTL at least 2 weeks before the beginning of the server move, to the lowest accepted value.

But as I can understand @Dylan is a little bit late now, and he is going to have problems for sure.
What I implemented, simply resolves the queries done against the old DNS, with the new IP addresses. This has nothing to do with "propagation speed up". It's just a really dirty workaround in order resolve some parts of the problem.

The rest, is cached somewhere in multiple parts of the internet, where you have no control... So... Just wait...

**flames** · May 31st 2017

I used iptables in such case. first migrated customer data, then redirected traffic for service ports to new server ip.
do this on your old server:

Code

sysctl net.ipv4.ip_forward=1
iptables -t nat -A PREROUTING -p tcp --dport 80 -j DNAT --to-destination new-host-ip:80
iptables -t nat -A PREROUTING -p tcp --dport 443 -j DNAT --to-destination new-host-ip:443
iptables -t nat -A PREROUTING -p tcp --dport 25 -j DNAT --to-destination new-host-ip:25
iptables -t nat -A PREROUTING -p tcp --dport 587 -j DNAT --to-destination new-host-ip:587
iptables -t nat -A PREROUTING -p tcp --dport 110 -j DNAT --to-destination new-host-ip:110
iptables -t nat -A PREROUTING -p tcp --dport 143 -j DNAT --to-destination new-host-ip:143
iptables -t nat -A PREROUTING -p tcp --dport 465 -j DNAT --to-destination new-host-ip:465
iptables -t nat -A PREROUTING -p tcp --dport 995 -j DNAT --to-destination new-host-ip:995
iptables -t nat -A PREROUTING -p tcp --dport 993 -j DNAT --to-destination new-host-ip:993
iptables -t nat -A PREROUTING -p tcp --dport 21 -j DNAT --to-destination new-host-ip:21
iptables -t nat -A POSTROUTING -j MASQUERADE

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when your dns is propagated, you can remove those rules or disable your old server

Forward all domain queries to new server

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