Change DNS TTL before changing the IP's of target servers.

[nmalviya]

We have seen issues in which customers tends to change the IP addresses of the target server without modifying the DNS TTL.

Hence it will land in a situation where the proxies are not reachable. Since the MPs will still try to connect with the old IPs.These old IP's still exists in our DNS cache, because it is not updated after changing the IP address.

DNS servers in Apigee only act as forwarder to the external domain. Therefore it is very necessary to check the DNS TTL for the external domain, before changing the IP address. So that it can be updated on Apigee side as well.

DOMAIN=<domain name >; dig +noall +answer $DOMAIN @$(dig NS $DOMAIN +short|head -n1)

For example:

DOMAIN="google.com"; dig +noall +answer $DOMAIN @$(dig NS $DOMAIN +short|head -n1)

google.com.		300	IN	A	172.217.31.206

Here the TTL for google.com is 300 seconds. For most of the other domains we have seen it to be set for 86400 seconds which is 24 hours. Reason why the proxies cannot be accessed for a day after changing the IP addresses.

To lower the TTL setting on the NS record in a AWS Route 53 hosted zone, follow below steps:

Sign in to the AWS Management Console and open the Route 53 console.

1. Choose Hosted Zones in the navigation pane.
2. Choose the name of the hosted zone.
3. Choose the NS record, and choose Edit.
4. Change the value of TTL (Seconds). We recommend that you specify a value between 60 seconds and 300 seconds (5 minutes).
5. Choose Save changes.

To lower the TTL setting on the NS record in GCP cloud DNS, follow below steps:

Sign in to the Google Cloud Console and navigate to Network Services.

1. In the Cloud Console, go to the Cloud DNS zones page
2. Click the zone for which you want to view the resource record set.
3. On the Zone details page, next to the resource record set that you want to update, click Edit icon.
4. Enter the time to live (TTL) for the resource record set—for example, 300
5. Select the TTL unit—for example, Seconds
6. After making the updates, click Save.

[pheneendragadip]

We faced exactly same issue. Couple of our target servers DNS's are updated with wrong IP's and due to which we had issues.

We corrected the DNS entry by removing the wrong IP's and later we updated DNS TTL to 5 mins.

But still we see that apigee is resolving wrong IP's. Is there any way clear the DNS cache at APIGEE. We are on APIGEE SAAS.

Thanks.

[#3]

I would suggest if you are using target server load balancer variable, then just delete the target server and then add again, else use another loadbalancer variable.