4 IP Services and Address Management Free Online FlashCards

What does a host need for IP connectivity?

A host needs a valid address and prefix, a functioning interface, and a path to the destination. For a remote subnet, it sends traffic to its default gateway.

What troubleshooting sequence helps isolate an IP connectivity problem?

Check the local interface and address, ping the local gateway, test a remote IP address, then test a DNS name. If the remote IP responds but its name does not, investigate DNS.

What are the four steps in the DHCP DORA exchange?

The DORA exchange is Discover, Offer, Request, Acknowledgment: the client discovers a server, receives an offer, requests an address, and gets an acknowledgment.

Why configure a DHCP relay when the server is on another subnet?

A relay on the client-facing Layer 3 interface forwards DHCP messages to a server on another subnet. Cisco IOS commonly uses `ip helper-address`.

How does SLAAC help an IPv6 host configure itself?

SLAAC lets a host form an address from a router-advertised prefix and check for duplicates. Hosts learn default-router information from Router Advertisements.

How do DNS A and AAAA records differ?

An A record maps a name to an IPv4 address; an AAAA record maps a name to an IPv6 address.

Why does a successful DHCP lease not prove DNS is working?

DHCP commonly supplies the resolver address, but it does not perform DNS resolution. A successful DHCP lease does not prove that name resolution works.

Which transport-layer port does DNS use?

DNS normally uses UDP port 53 for queries and can use TCP port 53 when needed.

When is static NAT useful?

Static NAT creates a fixed one-to-one mapping between an internal address and an external address, useful when an internal service needs a consistent external address.

What security limitation should you remember about NAT?

NAT translates IP address information, but it is not by itself a firewall or a substitute for security policy.

What does NTP stratum indicate?

NTP synchronizes device clocks. Stratum indicates distance from a reference clock in the synchronization hierarchy; it is not a direct measure of time accuracy.

Which UDP ports does IPv4 DHCP use?

DHCP uses UDP port 67 on the server and UDP port 68 on the client.