All practice questions

A network administrator is troubleshooting an authentication service failure where an internal enterprise application requires reverse DNS verification before granting access to incoming clients. The administrator runs the command `dig -x 192.168.50.25` and receives the following output:

text
;; QUESTION SECTION:
;25.50.168.192.in-addr.arpa. IN PTR

;; AUTHORITY SECTION:
50.168.192.in-addr.arpa. 3600 IN SOA ns1.corp.internal. hostmaster.corp.internal. 2026072701 7200 3600 1209600 3600

Which resource record configuration must be added to the authoritative zone to resolve the hostname verification failure?

A network engineer is investigating why enterprise client endpoints fail to locate a local software update repository server. According to system documentation, client agents perform a DNS query to discover service location details, including the designated port number, priority, and weight for load balancing.

The engineer executes the following command during troubleshooting:

text
$ dig +noall +answer _update._tcp.corp.example.com
_update._tcp.corp.example.com. 3600 IN CNAME repo1.corp.example.com.

Based on the diagnostic output, which of the following actions must the administrator take on the authoritative DNS server to resolve the discovery issue?

A network administrator is troubleshooting an issue where secondary DNS servers are unable to complete full zone transfers from the primary master DNS server across an internal firewall boundary. Standard client host name lookup queries across the firewall operate successfully. Which transport layer protocol and port number must be permitted on the firewall to allow zone transfers to complete?

An enterprise network administrator is deploying a new edge connection to an external Internet Service Provider (ISP) to exchange public routing information across autonomous boundaries. The internal network currently uses OSPF for internal routing. Which routing protocol should be deployed on the edge router facing the ISP, and what is the primary reason for this selection?

A network engineer is configuring a default gateway for a VoIP phone subnet that has been allocated the IPv4 address block $172.20.48.0/20$. Which of the following IP addresses represents the last usable host address available for assignment within this subnet?

An organization hosts an internal web server at private IP address $192.168.1.50$ that must be accessible to external clients on the internet using the public IP address $203.0.113.10$. Inbound requests from the internet to destination port $80$ must consistently map to this internal server. Which network address translation technique should the network administrator implement on the edge firewall?

When an enterprise router receives an IP packet, it executes a standardized path selection hierarchy to determine the optimal route for packet forwarding. Place the following route evaluation steps in the correct sequential order from first decision criteria to last.

A client workstation needs to connect to an external server via FQDN. The workstation's local DNS cache is empty. Sequence the complete recursive and iterative DNS resolution steps in the exact order they occur, from the client's initial request to the receipt and caching of the final IP address response.

A network administrator is designing an IPv4 subnet for a new regional warehouse facility. The facility requires static and dynamic IP address assignments for $115$ endpoint devices, including inventory scanners, workstation PCs, and network printers. What is the maximum number of usable host IP addresses available in the smallest CIDR subnet mask that satisfies this host requirement?

A network administrator needs to configure a floating static route to serve as an automatic failover backup path for an internal network segment currently learned dynamically via OSPF ($192.168.10.0/24$, Administrative Distance of $110$). Which of the following route configurations will ensure the backup static route remains inactive in the routing table until the primary OSPF route fails?

An organization is deploying a new VoIP phone deployment on VLAN 30 ($192.168.30.0/24$). While existing desktop computers on VLAN 10 ($192.168.10.0/24$) successfully acquire dynamic IPv4 addresses from a centralized DHCP server at $10.1.1.50$, the newly installed VoIP phones on VLAN 30 fail to receive an IP address lease. Both VLANs terminate on a central Layer 3 core switch. Which of the following configuration changes on the Layer 3 core switch will resolve the IP addressing issue for the phones on VLAN 30?

A network administrator is configuring a dedicated VLAN for a new branch office security system. The system requires static IPv4 addresses for 12 IP cameras, 2 Network Video Recorders (NVRs), and 1 router default gateway interface. Which of the following CIDR subnet masks is the smallest mask that accommodates all required host IP addresses while minimizing wasted address space?

A systems engineer is configuring an edge router for a secondary data center. The site has 50 internal servers on the private IP range $10.20.0.0/26$ that require outbound Internet access to update external software repositories using a single public IP address ($203.0.113.10$). Additionally, external administrators must be able to initiate inbound SSH connections directly to a dedicated internal management server at $10.20.0.5$. Which combination of address translation implementations should the engineer configure on the edge router?

A network engineer is troubleshooting an outbound connectivity issue at a branch office where 500 workstations on the $10.50.0.0/22$ internal network access external services through a router configured with Port Address Translation (PAT) on a single public IP address ($198.51.100.1$). Users report that while standard web traffic functions without issue, a legacy proprietary monitoring application that transmits raw IP packets (using custom IP protocol 99 without TCP/UDP transport headers or unique layer-4 session identifiers) allows only one internal host at a time to communicate with a remote server. Which of the following best explains why PAT fails to multiplex multiple simultaneous connections for this application?

Match each enterprise address translation requirement or descriptor on the left with the corresponding Network Address Translation (NAT) implementation type or address classification on the right.

Match each DNS resource record type to its corresponding technical description or administrative function within an enterprise DNS infrastructure.

A network technician is planning to install a new $2\text{U}$ server into a server room enclosure. Before mounting the hardware, the technician needs to review the exact vertical position, slot placement, and available rack unit space inside the equipment cabinet. Which of the following documentation types should the technician consult?

A network engineer is provisioning a dedicated IP address pool for an automated distribution center's IoT sensor array using the IPv4 network block $172.24.16.0/23$. How many usable IPv4 host addresses are available for assignment to end devices within this subnet?

A logistics company is connecting $80$ handheld scanner devices on a warehouse subnet ($172.16.10.0/24$) to a cloud inventory management platform. The ISP has assigned a single usable public IPv4 address ($198.51.100.45$) to the warehouse router's external interface. During testing, technicians observe that only one handheld scanner can access the cloud platform at any given time, while outbound connections from all other devices fail. Inspection reveals the router was configured with standard dynamic NAT without port mapping. Which configuration change should the network technician make to enable all $80$ scanners to communicate over the internet simultaneously?

A network operations engineer is auditing firewall configurations and service rules across enterprise infrastructure. Match each protocol and default transport port on the left with its corresponding functional application on the right.