This is definitely a DNS resolution problem. Either your API Gateway doesn't have a proper DNS configuration, the DNS servers that are configured can't be reached, or they can't resolve external domain names.
To verify, login to your API Gateway using the privileged root shell and type this command:
nslookup www.google.co.in
You should see this:
[root@yourapigateway ~]# nslookup www.google.co.in
Server: yourdnsserver
Address: yourdnsserver#53
Name: www.google.co.in
Address: 172.217.2.163
If it doesn't resolve, check your DNS configuration: cat /etc/resolv.conf