IP services

Which four-step process does a DHCP client use to obtain an address?

• A Request, Offer, Discover, Ack
• B Discover, Offer, Request, Ack ✓
• C Offer, Discover, Ack, Request
• D Discover, Request, Offer, Ack

Answer: The DHCP DORA process is Discover, Offer, Request, Acknowledge.

What is the primary purpose of Network Address Translation (NAT)?

• A Encrypt traffic between sites
• B Translate private addresses to public addresses for Internet access ✓
• C Assign IP addresses to hosts dynamically
• D Resolve domain names to IP addresses

Answer: NAT translates private RFC 1918 addresses to public addresses, conserving public IPv4 space.

Which NAT variation maps many private addresses to a single public address using different port numbers?

• A Static NAT
• B Dynamic NAT
• C PAT (NAT overload) ✓
• D Twice NAT

Answer: Port Address Translation (PAT), or NAT overload, multiplexes many inside hosts onto one public IP using unique source ports.

Which UDP ports does a DHCP server and client use?

• A 67 (server) and 68 (client) ✓
• B 53 and 54
• C 80 and 443
• D 20 and 21

Answer: DHCP servers listen on UDP 67 and clients on UDP 68.

Which protocol and port does DNS primarily use for standard name resolution queries?

• A TCP 53
• B UDP 53 ✓
• C UDP 67
• D TCP 80

Answer: DNS uses UDP port 53 for most queries; TCP 53 is used for zone transfers and large responses.

What does a DHCP relay agent configured with the 'ip helper-address' command allow?

• A Encryption of DHCP traffic
• B Forwarding of DHCP broadcasts to a server on a different subnet ✓
• C Assigning static addresses only
• D Blocking rogue DHCP servers

Answer: The 'ip helper-address' command lets a router relay DHCP broadcasts as unicast to a server on another subnet.