of ad substitution whereby a domain that serves ads is entirely swapped out with one serving more local ads to some subset of users. This is especially likely in countries, notably Russia, India and China, where advertisers often refuse to pay for clicks or page views. DNS-level blocking of domains for non-commercial reasons is already common in China. Recursive Local VPN On Android, apps can run a local VPN connection with its own host filtering ability and DNS address without requiring root access. This approach allows ad blocking app to download ad blocking host files and use them to filter out ad networks throughout the device. AdGuard, Blokada, DNS66, and RethinkDNS are few of the popular apps which accomplish ad blocking without root permission. The ad blocking is only active when the local VPN is turned on, and it completely stops when the VPN connection is disconnected. The convenience makes it easy to access content blocked by anti-adblock scripts. This approach optimizes battery usage, reduces internet slowdown caused by using external DNS or VPN ad blocking and needs overall less configuration. Hardware devices Devices such as AdTrap or Pi-hole use hardware to block Internet advertising. Based on reviews of AdTrap, this device uses a Linux Kernel running a version of PrivProxy to block ads from video streaming, music streaming, and any web browser, while PiHole act as local DNS to block advertisement servers, stopping connected devices from showing most ads. Another such solution is provided for network-level ad blocking for telcos by Israeli startup Shine. By external parties and internet providers Internet providers, especially mobile operators, frequently offer proxies designed to reduce network traffic. Even when not targeted specifically at ad filtering, these proxy-based arrangements will block many types of advertisements that are too large or bandwidth-consuming, or that are otherwise deemed unsuited for the specific internet connection or target device. Many internet operators block some form of advertisements while at the same time injecting their own ads promoting their services and specials. Economic consequences for online business Some content providers have argued that widespread ad blocking results in decreased revenue to a website sustained by advertisements and e-commerce-based businesses, where this blocking can be detected. Some have argued that since advertisers are ultimately paying for ads to increase their own revenues, eliminating ad blocking would only dilute the value per impression and drive down the price of advertising, arguing