How to check proper DNS resolution based in gelocation for SAP Cloud for Customer
Check of proper DNS resolution is important since SAP Cloud for Customer take advantage Akamai network acceleration solutions to improve the path of the middle mile, but still the first mile could be a problem if the DNS configuration is not set correctly. To verify this, we need to follow these steps:
- Identify IP of Akamai server. Commands like “nslookup” or “dig” can be used to query the DNS server and get IP of the Akamai Edge Server, by example
- Identify geolocation of Akamai server. There are multiple web sites that offers geo location information for IPs from different databases, some of these tools are free, and maybe some might have outdated information. The recommendations will be to retrieve the information from multiple of these web sites to validate the accuracy. The following is a list of web site which offer geolocation information for IP:
https://www.ultratools.com/tools/geoIpResult
https://www.maxmind.com/en/geoip-demo
- If require, identify IP used to access Internet. There are different methods to identify the IP used to connect to Internet, one simple way is by searching in Google, searching the following term “what is my ip” this method will show you the public IP used to connect to the Internet
- If require, identify geolocation of public IP. The same steps follow before to get the geolocation of the Akamai server can be follow to get the geolocation of the IP used to connect to the Internet
- If require, identify IP of DNS server. Using commands like ipconfig /all, nslookup, or dig is possible to identify the IP of the DNS server, sometimes it might be required to ask the network administrator for this information
- If required, identify geolocation of DNS server base in IP. The same steps follow before to get the geolocation of the Akamai server can be follow to get the geolocation of the DNS server based in the IP
Once we have the IP and geolocation of the Akamai server, DNS server and from where we are connecting to the Internet, it will possible to determine if all of them are located in the same region and further more validate that the end user is located in same region as well.
Thanks for the sharing. However, we encountered an issue that Akamai misrouted to Europe while user located in China. What the weird is it usually happens during evening time. We don't understand why Akamai doesn't route correcly and don't know whom we can contact. Would you please help?
Regards,
Felix
Hi Felix,
China is tricky, we do have China CDN as part of the offering of Akamai. The best and official way to proceed will be by creating an incident to analyze tracerts outputs and if the change of routing is happening in the middle mile we have to involve Akamai, but if what you are talking is about the last mile, it is most probable related with DNS or ISP.
Zareh
Hi Zareh
Thanks for providing these articles re network performance and Akamai - very useful.
We are based in New Zealand, using the SAP Sydney, Australia data centre (C4C). When I ran these tests I found it is using an Akamai server in MA, USA.
I raised an incident (3500265961) but am being told "The URL which is Akamai enabled always gives dynamic IP so it depends on algorithm by which path the IP can travel to reach destination in fastest path by using Akamai server. It also used an optimized routing in the Internet."
I'm a little confused by this as I would have thought being served by Akamai in MA, USA would add a significant overhead.
Would appreciate your thoughts?
Regards Mark
Hi Mark,
I doubled check and the IP of the Akamai Edge server captured on the incident is actually located in Auckland. Most probable the public IP geolocation service is out of the date.
Zareh
P.D. another way to have a feeling if the IP you are hitting is in another continent, it is by getting the latency, by example using "ping" pings with +300 ms you can think is in another continent unless there is high package loss.