Computer Networks

An IP address is a Layer 3 address, also known as Network layer address. Network layer addresses have two parts: the network part and the host part. The subnet mask shows that it is a Class C network address.

Since the ping to 127.0.0.1 (loopback) is successful, the TCP/IP stack is properly installed and functioning. However, inability to access the company network despite successful loopback suggests a subnet mask misconfiguration. An incorrect subnet mask causes the host to miscalculate which IP addresses are on the local subnet versus remote networks, leading to incorrect routing decisions. IP address being wrong would cause different errors, unplugged cables wouldn't allow loopback success, and network card failure would prevent loopback from working.

In EIGRP, routes learned from other EIGRP routers have an administrative distance (AD) of 90 by default. This AD value will appear in Router1's routing table for networks like 172.16.0.0 that are learned via EIGRP. Administrative distance is a trustworthiness metric used to rate routes from different routing protocols. Router1 would not have 6 directly connected networks in this scenario (it would have directly connected plus EIGRP-learned routes), EIGRP metrics are composite values based on bandwidth and delay (not simply 1), and the forwarding interface can change based on routing decisions.

The administrator can ping the mail server (Layers 1-3 working) and resolve the mail server name via DNS (Layer 3 + DNS application working), but email retrieval fails. Since lower-layer connectivity is confirmed and name resolution works, the problem must be at the Application Layer where email protocols (SMTP, POP3, IMAP) operate. This could involve email service configuration, authentication issues, firewall blocking email ports, or the email daemon not running. Physical, data link, and network layer issues would typically prevent ping or DNS from working.

In traditional inter-VLAN routing, each VLAN must be assigned to the correct switch port. If the port connecting computer 1 (Fa0/11) is in the wrong VLAN, traffic from the router won't reach computer 1 even though it can reach computer 3. The router's subinterfaces are configured for specific VLANs, so the switch port must match the VLAN assignment.

An incorrect subnet mask causes a host to misidentify which networks are local versus remote. Host A can communicate with the server farm because the incorrect mask makes it appear local, but internet traffic fails because routing decisions become invalid. The gateway address is correct (proven by server farm connectivity), but the subnet mask causes the host to apply wrong network boundaries.

The ACL must filter traffic as it leaves toward the internet. Applying it outbound on S0/0/0 (the WAN interface to the internet) allows the ACL to examine traffic before it leaves the router. The permit statement for 192.168.1.0/24 is processed first, allowing that internal traffic, while the deny statement for internet traffic takes effect after. Applying on Fa0/0 would block internal-to-internal traffic.

Static routing uses manually configured routing table entries that don't change automatically. Dynamic routing uses protocols to automatically update routes. Interior routing refers to internal network routing, and 'standard' is not a routing type. Static routing requires network administrators to manually enter and maintain all routing information.

The question states the administrator enters commands and Frame Relay PVCs are inactive. Without seeing the exhibit, the claimed answer is A (incorrect DLCI numbers). This is plausible because mismatched or wrong DLCI numbers would prevent PVCs from becoming active. The other options (interface needs to be point-to-point, missing cisco keyword, single router limitation) are less likely to cause the described issue.

In VTP (VLAN Trunking Protocol), transparent mode switches (SW3) receive and forward VTP updates but don't synchronize their own VLAN database. Client mode switches (SW4) receive updates AND synchronize their VLAN configuration. Server mode (SW1) sends updates. Therefore SW3 receives but doesn't sync, while SW4 both receives and syncs. Option D correctly describes this behavior.

The network layer (Layer 3) header, such as in IP packets, contains the destination host's IP address, which allows the packet to be routed across multiple networks to reach the correct destination host. Layer 3 provides logical addressing and routing. The destination device on local media is found using Layer 2 (MAC) addressing, while the source application is identified at Layer 4 (ports) or Layer 7.

In Spanning Tree Protocol, the designated port is the port on a network segment that has the best path to the root bridge. Each segment must have exactly one designated port, and only the designated port and root port can forward traffic. Non-designated ports are placed in blocking state to prevent loops. The designated port must exist and forward for traffic to flow on that segment.

Named ACLs allow you to edit the access list by inserting or deleting individual statements anywhere in the list without removing and recreating the entire ACL. Numbered ACLs only allow you to add new statements at the end and require complete removal to make changes in the middle. All the other capabilities listed (filtering by protocol, protocol suite, addresses) are available in both numbered and named ACLs.