I have been reading good discussions and comments here for scea, some of my experience might be helpful for others too. The part 1 test is not very difficult, guess it's not designed to be tough but rather be a motivation to learn, indeed I have learned a lot.
I was wrong on two questions, one in security(50%) and one in legacy connectivity(80%), so must be 2 on security and 5 on the other.
1. read cade-roberts book very carefully.
2. questions use syllabus closely, so make sure you have a good understanding on each. e.g which part of firewall would affect protocols,
port filering, address filering, content filering, address translation,
http, https, iiop, jrmp
so there are 4*4=16 cases you can investigate.
3. mock tests are not very close to real one, but it's good for learning, i scored usually 75-90% on them.