Which layer-2 exploit blocks genuine clients from acquiring IPv4 addresses? Attacks using DHCP exhaustion, flooding, and MAC address spoofing Spoofing of ARP

1) What is the difference between a basic packet filtering firewall and a stateful packet filteringfirewall?2) Which network traffic uses TCP protocol and which uses UDP protocol? Can someone take the time to answer these for me? I'm doing a HW and am stumped.

QUESTION 47 Man in the middle attack can be avoided by using public private key and nonce. True False     QUESTION 48 SMTP is a push based proctols True False     QUESTION 49 TLS runs in the application layer and provides a secure communication True False     QUESTION 50 Count-to-infinity may happen in link state based shortest path algorihtms. True False     QUESTION 51 HTTP protocol defines GET requests and Responses True False     QUESTION 52 TCP divides the bandwith fairly among peers True False

How can an attacker with host access (either an untrustworthy host, or an attacker who has compromised the host.  This is also known as a host attack) attack a system that uses passwords to authenticate users, and which stores the passwords in plain text?