I was hoping to complete my CCNA certification today. Sadly, I came close but didn't quite make it. A large part of my problem was the simulation question. For the life of me I couldn't get a serial interface to communicate with its peer on a /30 network. I verified the IP on my router was a valid host in the range. Interface was up/up. The interface was configured with hldc and a clockrate. I also couldn't get any information for the peer using sh cdp neighbors. Ping failed. Since that was the first link you had to bring up to do anything else, it was a deal-breaker when I couldn't get it going. Any ideas for things I might have overlooked.