# Other common problems

Source: https://developer.avalara.com/avatax-for-ap/snt7895583305067/

# Other common problems

Diagnose and resolve common issues related to routing, authentication, firewalls, andmore.

PROBLEM TYPE

STEPS TO DIAGNOSE

Routing Problems

Do your routers have the latest software? Have they been rebootedrecently, or are there too many hops between your network andthe outside world?

-   If your network is using a direct connection with a localinternet service provider, does your connection resetregularly?
-   If the connection is permanent or business-class, does yourISP offer metrics to help you measure response time?
-   If you have a more advanced network using [Border GatewayProtocol](https://en.wikipedia.org/wiki/Border_Gateway_Protocol) routing, you will need to talk to yournetwork engineering team. BGP issues are very challenging toreview and are beyond the scope of this article.

Due to security issues, Avalara's servers don't respond to pingrequests. This means that network traces from software like[traceroute or tracert](https://en.wikipedia.org/wiki/Traceroute)aren’t able to provide accurate route timings.

Authentication Problems

Try using the [Ping API](https://developer.avalara.com/api-reference/avatax/rest/v2/methods/Utilities/Ping/), or switch tousing an [AvaTax SDK](https://developer.avalara.com/sdk/), which hasprebuilt and tested authentication code.

Firewall Problems

To use AvaTax, you must enable access to all IP addressesidentified by these DNS names:

-   Sandbox environment: [https://sandbox-rest.avatax.com](https://sandbox-rest.avatax.com/)

-   Production environment: [https://rest.avatax.com](https://rest.avatax.com/)

AvaTax is a dynamic product, and its IP addresses may changeregularly. AvaTax doesn’t support firewalls that filter onindividual IP addresses.

Ethernet Problems

Check the quality of your wiring and the auto negotiate settingson your Ethernet devices. Bad wiring or devices with mismatchedspeed settings are easy to overlook! You can run `netstat-s` on a windows machine or `ifconfig -a`on a Linux machine to detect whether an unusual number of badpackets are coming through your network. If you have a performancemismatch, try checking with your network administrator to see if thecabling can be improved.

Host Files / IP Address Hardcoding / DNS Caching

AvaTax doesn’t support hardcoded IP addresses or host files. Touse AvaTax, you must resolve DNS names dynamically. Your DNS servershould respect the DNS time-to-live (TTL) values; Avalara publishesDNS TTL values designed to permit our operations team to adjust ourconnectivity in response to changing network conditions.

Proxy Server Problems

AvaTax isn’t designed for environments using proxy servers. Proxyservers can cause latency and connectivity problems when callinghigh performance APIs like AvaTax. If your company policy requires aproxy server, consult your proxy provider for how to configurecorrectly the proxy to work with AvaTax.

DNS Time-To-Live

Avalara makes changes to our domain name system recordsperiodically. Ensure that your software respects the DNStime-to-live values and that your software periodically contacts DNSto update its name lookups. Some software applications, includingsome Java JRE versions, may need to be updated to ensure they handlethe "ttl" or "time-to-live" values correctly. If you experienceproblems with occasional DNS changes, check the documentation foryour operating system, programming language, or developmentenvironment to ensure your software handles TTL valuescorrectly.

Need SSL Certificate Verification

Some web clients (such as cURL for Windows) will require you todownload the Avalara AvaTax SSL public keychain and install itinto your client’s keychain repository. If the client programrequests that you specifically accept and trust Avalara's webcertificate, here's how to proceed:

1.  Go to [VeriSign RootCA](https://www.tbs-certificates.co.uk/FAQ/en/34.html); and follow the instructions.

2.  Save the file in your preferred directory, for example,**certs-ca-bundle.crt**.

3.  Register that file following your standard certificatestore process.