I have configured the portal for arcgis , I want to know that the basemaps are avaliable only when i connect to internet.
what can be done for this i want to use the basemaps without connecting to internet.
by default basemaps in portal for arcgis consumed online tiledservices from services.arcgisonline.com, so the basemaps only available if you have internet connection.
if you want to access basemap without internet connection (offline or intranet). you can publish your own basemap in your arcgis server (generate cache in you map services for best performance). one of DVD installer of ArcGIS Server included cached basemap, however the LOD is limited. once your map services for basemaps are ready, you can following this step.
1. create new group in your portal for arcgis for example name it as local basemap (share group for everyone)
2. add your map service to your portal for arcgis, save it as webmap and share it to group local basemap
3. go to my organization > edit settings > select Map
3. in Basemap Gallery, change default to local basemap (your group for basemap)
4. in Default basemap, select one of your custom basemap name (name of this referred to your webmap name)
5. save settings.
Apart from usage of your own maps/images as basemaps as mentioned by khairul amri, you could use Data Appliance for ArcGIS | What You Get which is a premium service of Esri. Contact your local Esri distributor for more details.
Also check the following