"Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."
- Albert Einstein
Which WAN encapsulations can be configured on an asynchronous serial connection?
1 and 2
2 and 4
3, 4 and 5
All of the above
Please do not freak out because ATM is an answer to this question. ATM is not covered in depth on the CCNA exam. PPP is mostly used for dial-up (async) services, but ATM could be used as well, though it typically is not used anymore since PPP is so efficient.