Practice
Solution
Step 1: Identify the role of ARP
ARP (Address Resolution Protocol) is specifically designed to map IP addresses to MAC addresses within a local network segment.Step 2: Why not DNS?
DNS resolves domain names to IP addresses, not MAC addresses.Step 3: Why not DHCP?
DHCP assigns IP addresses dynamically but does not resolve MAC addresses.Step 4: Why not routing table?
Routing tables determine the next hop IP address but do not resolve MAC addresses.Final Answer:
Option B -> Option BQuick Check:
ARP is the protocol that resolves IP to MAC addresses on local networks [OK]
- Confusing DNS with ARP
- Thinking DHCP handles MAC resolution
Solution
Step 1: Identify PDU names per OSI layer
Application Layer and Presentation Layer use 'Data', Transport Layer uses 'Segment', Network Layer uses 'Packet', Data Link Layer uses 'Frame', Physical Layer uses 'Bits'.Step 2: Follow encapsulation order
Data is segmented, then packets are created, frames are formed, and finally bits are transmitted.Final Answer:
Option C -> Option CQuick Check:
Correct encapsulation order matches OSI layering [OK]
- Confusing order of PDUs
- Mixing up Segment and Packet roles
- Reversing encapsulation direction
Solution
Step 1: Understand certificate chain transmission
The certificate chain is sent in plaintext during the handshake because encryption is not established yet.Step 2: Evaluate each statement
A: Correct, chain includes server and intermediate certificates.
B: Correct, client must trust root CA.
C: Incorrect, chain is sent unencrypted.
D: Correct, invalid certificates cause rejection.Final Answer:
Option A -> Option AQuick Check:
Certificate chain is sent before encryption is established, so it cannot be encrypted.
- Assuming certificate chain is encrypted during handshake
- Confusing trust anchor with intermediate certificates
- Ignoring certificate expiration impact
Solution
Step 1: Understand subnet change impact
IP addresses are subnet-specific; moving to a new subnet requires obtaining a new IP address.Step 2: Analyze DHCP behavior
The client must initiate a new DORA sequence to get a valid IP from the new DHCP server.Step 3: Evaluate other options
Options B, C, and D are incorrect because the old IP lease is not valid on the new subnet and lease renewal is with the original server only.Final Answer:
Option B -> Option BQuick Check:
Subnet change triggers new DHCP discovery and IP assignment.
- Assuming IP leases are portable across subnets
- Believing lease renewal works with a different DHCP server
- Thinking client can keep old IP without releasing
Solution
Step 1: Understand PAT port mapping
PAT uses unique external source ports to distinguish simultaneous connections even if internal source ports collide.Step 2: Analyze options
The router assigns different external source ports to each connection to avoid conflicts correctly states that the router assigns unique external ports. The router forwards both connections using the same external source port, causing packet mix-up is false; PAT prevents port conflicts. The router blocks the second connection because the source port is already in use is incorrect; connections are not blocked due to port reuse internally. The router changes the destination port on the external server to differentiate connections is wrong; destination ports on external servers are not changed by PAT.Final Answer:
Option D -> Option DQuick Check:
PAT ensures unique external source ports per connection [OK]
- Assuming PAT cannot handle internal source port collisions
- Believing PAT blocks connections with same internal ports
- Thinking PAT changes destination ports on external servers
