ECP-206 Ericsson Certified Associate - IP Networking Free Practice Exam Questions (2025 Updated)

The device that will fragment IPv6 packets is the source host. Fragmentation is a process of dividing a large packet into smaller pieces that can fit the maximum transmission unit (MTU) of the network link. In IPv4, fragmentation can be performed by either the source host or any intermediate router along the path. However, in IPv6, fragmentation is only allowed at the source host, and routers are not allowed to fragment packets. This reduces the processing overhead and complexity at routers and avoids potential fragmentation attacks. If a router receives an IPv6 packet that is too large for the next-hop link, it will drop the packet and send an ICMPv6 Packet Too Big message back to the source host56.

References: IPv6 address - Wikipedia, IPv6 Fragmentation - Cisco

Two protocols that apply to both IPv4 and IPv6 are:

SNMP: This stands for Simple Network Management Protocol, which is a protocol that allows network administrators to monitor and manage network devices such as routers, switches, servers, printers, etc. SNMP uses a client-server model, where an SNMP manager (client) can query or configure an SNMP agent (server) on a network device using SNMP messages. SNMP can operate over both IPv4 and IPv6 networks56.

DNS: This stands for Domain Name System, which is a protocol that translates human-readable domain names (such as www.example.com) into numerical IP addresses (such as 192.0.2.1 or 2001:db8::1) that identify network devices. DNS uses a hierarchical distributed database of name servers that store and resolve domain names and IP addresses. DNS can support both IPv4 and IPv6 addresses78.

References: Simple Network Management Protocol - Wikipedia, SNMP over IPv6 - Cisco, Domain Name System - Wikipedia, DNS for IPv6 - Cisco

Within an IGP area, routers advertise information about themselves and relay information delivered by neighbors. This is how link-state routing protocols such as OSPF and IS-IS work. They flood information about the network topology to all routers in the same area or domain. That information is then used to build a complete network connectivity map and to calculate the shortest path to destinations. Routers do not summarize or discard information within an area, unless they are configured to do so by some filtering mechanism. References: Ericsson IP Networking - Routing Protocols, IP Routing: ISIS Configuration Guide - IS-IS Overview and Basic Configuration

Two statements that are true about router node hardening are:

Any unnecessary services should be disabled within each context. Router node hardening is a process of securing a router from unauthorized access and attacks by applying various configurations and policies. One of these configurations is to disable any services that are not needed for the router’s functionality or purpose, such as telnet, ftp, http, etc. This reduces the attack surface of the router and prevents potential exploits of these services91.

Enabling syslog ensures system events are logged to a remote server. Syslog is a protocol that allows a router to send system messages and events to a remote server for logging and analysis. By enabling syslog on a router, network administrators can monitor the router’s activity and performance, troubleshoot problems, detect anomalies, and audit security events101.

References: Cisco Router Hardening Step-by-Step | SANS Institute, Security Hardening Checklist Guide for Cisco Routers/Switches in 10 Steps, CCNA SEC: Router Hardening - Cisco Press

Two statements that are true regarding the LSP are:

The LSP refers to a sequence of routers that forward the MPLS packet based on labels. An LSP is a Label Switched Path, which is a path through an MPLS network that is established by signaling protocols such as LDP or RSVP-TE. An LSP consists of a sequence of routers (called Label Switching Routers or LSRs) that forward packets based on labels rather than IP addresses. Labels are short fixed-length identifiers that are attached to packets at the ingress router and removed at the egress router. Labels can be swapped or popped at intermediate routers according to their label forwarding tables78.

The LSP refers to a sequence of routers that add, remove, or change label values along the path. As mentioned above, an LSP consists of a sequence of routers that forward packets based on labels. Along the path, different routers may perform different operations on the labels depending on their role and configuration. The ingress router adds one or more labels to the packet before sending it into the MPLS network. The egress router removes all labels from the packet before sending it out of the MPLS network. The intermediate routers may swap one label with another label according to their label forwarding tables. This process is called label switching78.

References: MPLS Fundamentals: 3 - MPLS Packet Forwarding, Multiprotocol Label Switching - Wikipedia

The Area ID to which the router belongs is 49.00F0.0100. The Area ID is a variable-length field in the NSAP address that identifies the area to which the router belongs. The Area ID can be between 1 and 13 bytes long, but it must start and end with an octet (8 bits). The NSAP address is composed of three parts: the authority and format identifier (AFI), the area ID, and the system ID. The AFI is a one-octet field that indicates the format and authority of the rest of the address. The system ID is a fixed-length field of six octets that uniquely identifies the router within an area. The NSAP address also has a network selector (NSEL) field, which is a one-octet field that identifies the network layer service to which a packet should be sent. For IS-IS routers, the NSEL must always be 00.

In this question, the NSAP address is 49.00F0.0100.5012.3010.00. This means that:

The AFI is 49, which indicates a private address.

The Area ID is 00F0.0100, which is four octets long and starts and ends with an octet.

The system ID is 5012.3010, which is six octets long and identifies the router within the area.

The NSEL is 00, which indicates IS-IS.

Therefore, the answer is B.

References: Ericsson IP Networking - Routing Protocols, IS-IS NSAP address - Cisco Community, Understanding IS-IS NSAP Addresses - Todd Lammle, LLC, IS-IS - Nokia, Network service access point address - Wikipedia

The CLI command to obtain the software version in Ericsson Router 6000 products is show version. This command displays information about the software release, the hardware model, the serial number, the uptime, and the boot image of the router. References: [ERICSSON SMARTEDGE 600 HARDWARE MANUAL Pdf Download | ManualsLib], Ericsson Router 6000 Series - Ericsson

MTU mismatch would cause an IS-IS adjacency between two routers to fail. MTU stands for maximum transmission unit, which is the maximum size of a packet that can be transmitted on a link. IS-IS hellos are padded to the full MTU size, partly to allow a router to implicitly communicate its MTU to its neighbors. If two routers have different MTUs on their interfaces, they will not be able to exchange hellos properly, and their adjacency will not form or will be dropped34. To solve this problem, the MTUs on both interfaces must be configured to match.

SEL, context, and SysID are not fields that would cause an IS-IS adjacency failure. SEL stands for selector, which is a one-octet field that identifies the network layer service to which a packet should be sent. For IS-IS routers, the SEL must always be 005. Context is not a field in IS-IS packets, but rather a term used to describe the scope of routing information in different levels or areas6. SysID stands for system identifier, which is a six-octet field that uniquely identifies a router within an area. SysID does not have to match between two routers for them to form an adjacency7.

References: MTU Mismatch Problem in IS-IS - Cisco, IS-IS adjacency is not formed due to MTU mismatch - Cisco Community, IS-IS NSAP address - Cisco Community, Understanding IS-IS Routing Contexts - Juniper Networks, IS-IS - Nokia

Two statements that are correct for LDP are:

LSRs send UDP hello messages for neighbor discovery. LDP is a protocol that distributes labels for MPLS forwarding along the shortest path calculated by an IGP. LDP uses two types of messages: discovery messages and session messages. Discovery messages are used to discover and maintain adjacency with other LSRs that support LDP. Discovery messages are sent as UDP datagrams to the well-known multicast address 224.0.0.2 (all routers on this subnet) on port 64634.

LSRs use TCP to negotiate LDP session parameters. Session messages are used to establish, maintain, and terminate LDP sessions between LSRs. Session messages are also used to exchange label mappings, notification messages, and keepalive messages. Session messages are sent as TCP segments to port 64634.

References: Ldp | Microsoft Learn, Label Distribution Protocol - Wikipedia

The maximum number of unique VLAN IDs available is 4096. A VLAN ID is a 12-bit identifier that can range from 0 to 4095. However, VLAN ID 0 is reserved for tagging the priority of frames and VLAN ID 4095 is reserved for implementation use, so only VLAN IDs from 1 to 4094 are available for user configuration78. VLAN IDs are used to identify different broadcast domains or subnets on a Layer 2 network. VLAN IDs are carried in the IEEE 802.1Q tag in the Ethernet frame header.

References: What is a virtual LAN (VLAN) and how does it work with my managed switch? - NETGEAR Support, Virtual LANs (VLANs) - Cisco

Spanning-Tree is used for Ethernet loop avoidance. Spanning-Tree is a protocol that prevents loops in Ethernet networks by creating a logical tree topology of the network switches. Spanning-Tree blocks some of the redundant links between switches to ensure that there is only one active path between any two nodes in thenetwork. Spanning-Tree also detects and recovers from link failures by activating alternative paths when needed56.

References: Network loops and loop avoidance - Medium, Spanning Tree Protocol - Wikipedia

The statement that accurately defines an Autonomous System (AS) is that an AS is a set of routers under a single administration, using an interior gateway protocol and common metrics to route packets within the AS. An AS is a logical grouping of networks that share a common routing policy and operate under a single administrative authority. An AS can be a single network or a collection of networks that are interconnected by routers. An AS uses an interior gateway protocol (IGP), such as OSPF or IS-IS, to exchange routing information within the AS. An IGP uses common metrics, such as hop count or bandwidth, to determine the best path to each destination within the AS. An AS also has a unique number assigned by IANA, called an AS number (ASN), which identifies the AS in interdomain routing .

References: [Autonomous system (Internet) - Wikipedia], [What Is an Autonomous System? - Cisco]

In the exhibit, router R4 is performing a swap action. This means that router R4 is replacing the incoming label with a new label and forwarding the packet to the next hop along the LSP. In this case, router R4 receives a packet with label 20 from router R3 and swaps it with label 30 before sending it to router R5.

The exhibit shows an example of an MPLS network with four routers: R1, R2, R3, and R4. Router R1 is the ingress PE router and router R4 is the egress PE router. Router R2 and R3 are P routers. Router R1 assigns label 10 to the packet and sends it to router R2. Router R2 swaps label 10 with label 20 and sends it to router R3. Router R3 swaps label 20 with label 30 and sends it to router R4. Router R4 removes label 30 from the packet and forwards it based on its IP header or another label in the stack.

Therefore, the answer is D.

References: MPLS Label Switching | MPLS Operation | Push, Swap,Push ⋆ IPCisco, A Complete Guide to Multiprotocol Label Switching (MPLS) - G2, Multiprotocol Label Switching - Wikipedia

According to RFC1918, there are three network blocks reserved as private networks that are not allocated to any specific organization and are not routable on the public Internet. These are:

10.0.0.0/8 (10.0.0.0 - 10.255.255.255)

172.16.0.0/12 (172.16.0.0 - 172.31.255.255)

192.168.0.0/16 (192.168.0.0 - 192.168.255.255)

Out of these, only option B (10.254.1.0/24) falls within one of the private network blocks (10.0.0.0/8). Option A (172.16.1.0/9) is not valid because it exceeds the /12 prefix length of the private network block (172.16.0.0/12). Option C (193.168.1.0/24) is not valid because it does not belong to any of the private network blocks, and is actually assigned to RIPE NCC as a public network block . Option D (172.15.1.0/24) is also not valid because it does not belong to any of the private network blocks, and is actually assigned to ARIN as a public network block . References: RFC 1918: Address Allocation for Private Internets, Private network - Wikipedia, [RIPE NCC IPv4 Address Space Chart], [ARIN WHOIS Database Search]

The action that will influence BGP route selection within your AS is changing the default value of the local preference attribute. The local preference attribute is used to indicate the preference of a path among multiple paths learned from different external BGP neighbors or autonomous systems (ASes). The higher the local preference value, the more preferred the path is within your AS, and vice versa. The default value of local preference is 100, but you can change it using route maps or other configuration methods on your BGP routers. References: Ericsson IP Networking - Routing Protocols, BGP Attributes and Path Selection, BGP Local Preference Attribute: Controlling Traffic Like a Pro

 A reason for using VLANs in an IP network is to isolate hosts within the same IP subnet. VLANs (Virtual LANs) are logical grouping of devices in the same broadcast domain. VLANs are usually configured on switches by placing some interfaces into one broadcast domain and some interfaces into another. Each VLAN acts as a subgroup of the switch ports in an Ethernet LAN. VLANs allow network administrators to group hosts together even if the hosts are not directly connected to the same network switch. By using VLANs, hosts within the same IP subnet can be separated into different broadcast domains, which enhances security, reduces network congestion, and simplifies network management78.

References: 8 Different Types of VLANs in TCP/IP Networks, What is a VLAN? - Study-CCNA

Penultimate hop popping (PHP) is a function performed by certain routers in an MPLS enabled network. It refers to the process whereby the outermost label of an MPLS tagged packet is removed by a label switch router (LSR) before the packet is passed to an adjacent label edge router (LER). The purpose of PHP is to reduce the load on the LER, as it saves one cycle of label lookup. The LER can forward the packet based on its IP header or another label in the stack, without having to process the outer label. PHPfunctionality is achieved by the LER advertising a label with a value of 3 to its neighbors. This label is defined as "implicit-null" and informs the neighboring LSRs to perform PHP12.

References: Penultimate hop popping - Wikipedia, MPLS Penultimate hop popping - NetworkLessons.com