If you wish to preview files directly through a browser or download objects of .apk or .ipa type in the bucket, access the objects through a custom domain name.
You can set the parameter value of Content-Disposition in the custom object headers to inline via the COS console. When the browser supports the file format, it will open the file directly instead of downloading it. For the operation guide, see Custom Headers.

How Do I Directly Download a File in My Browser Without Previewing It?

You can set the parameter value of Content-Disposition in the custom object headers to attachment via the COS console. For the operation guide, see Custom Headers.
You can also set the request parameter value of response-content-disposition in the GET Object API to attachment to enable your browser to pop up a window for downloading the file. For the reference documentation, see GET Object.

Note:

To use the response-* parameter in a request, the request must be signed.

How Do I Determine If I Am Accessing COS Over a Private Network?

Intelligent DNS resolution is adopted for COS access endpoints, and the optimal linkage will be detected and provided for you to access COS over the Internet with different Internet Service Providers (ISPs). If you have deployed a service within the cloud platform for accessing COS, intra-region access will be automatically routed to a private network address. Cross-region requests do not support private network access and will be resolved to a public network address by default.

Ways to Determine Access Over a Private Network

Cloud products within the same region automatically access each other through private network connections, and the generated private network traffic incurs no traffic fees. Therefore, when you purchase different products, it is recommended that you choose the same region to save on fees.
To determine access over a private network, see the following method:
For example, when a CVM accesses COS, to determine whether a private network is used to access COS, use the nslookup command on the CVM to resolve the COS endpoint. If a private IP address is returned, the access between the CVM and COS is over a private network; otherwise, it is over a public network.

Note:

Generally, a private IP address takes the form of 10.*.*.* or 100.*.*.*, and a VPC IP address takes the form of 169.254.*.*.

Assume that examplebucket-1250000000.cos.city.yfm4.fsphere.cn is the address of the destination bucket; the Address: 10.148.214.13 below indicates that the access is over a private network.

nslookup examplebucket-1250000000.cos.city.yfm4.fsphere.cn

Server:         10.138.224.65
Address:        10.138.224.65  #53

Name:   examplebucket-1250000000.cos.city.yfm4.fsphere.cn
Address: 10.148.214.13
Name:   examplebucket-1250000000.cos.city.yfm4.fsphere.cn
Address: 10.148.214.14

What If the Error 403 Forbidden Occurs or Access Permission Is Rejected When I Perform Upload/Download and Other Operations?

Follow the steps below to troubleshoot the issue step by step:

Check if the following configuration information is correct:
BucketName, APPID, Region, SecretId, and SecretKey.
After ensuring that the above information is correct, check if you are using a sub-account for operations. If you are, check whether the root account has granted the sub-account the permissions. Otherwise, log in to the root account to grant the sub-account the permissions. For operations on granting permissions, see Authorization Cases.
If you are using a temporary key for operations, check whether the current operation is within the policy set when you get the key.
If you still cannot solve the problem after following the steps above, submit a ticket and contact us.

When I Upload a New File to a Bucket in Which Another File of the Same Name Exists, Will the Old File Be Overwritten or Will the New File Be Saved with a Different Version Name?

COS now supports the versioning feature. If versioning is not enabled for the bucket, when you upload a file to the bucket in which another file of the same name already exists, the old file will be directly overwritten; if versioning is enabled for the bucket, when you upload files to the bucket in which another file of the same name already exists, multiple versions of the object will co-exist.

What Is the Minimum Part Size of a Multipart Upload in COS?

1 MB minimum per part. For more information, see the document Specifications and Limits.

When Uploading a Large File with Multipart Upload, Can I Replace an Invalid Signature to Continue the Multipart Upload?

Yes.