In traditional IPv4 subnetting, a /30 is often used to connect two hosts directly, giving two usable IPs. However, MikroTik RouterOS (and as per RFC 3021) supports the use of /31 subnet masks for point-to-point links. A /31 provides exactly two IP addresses — which are both usable — and is ideal for conserving IP space on router-to-router links.
Subnet details for /31:
Total addresses: 2
Usable addresses: 2 (both can be assigned to endpoints, no broadcast)
Evaluation:
A. /31 →✅Supported by MikroTik for point-to-point links (2 hosts only)
B. /29 → Provides 6 usable IPs; more than needed for 2 hosts
C. /32 → Single host only; no communication possible with second device
D. /30 → Valid, but less efficient than /31
MTCNA Course Manual – IP Addressing and Point-to-Point Communication:
“MikroTik RouterOS allows the use of /31 subnets for point-to-point communication. Both IPs are usable.”
René Meneses MTCNA Guide – IP & Routing Concepts:
“For links between exactly two devices, /31 saves address space and is supported by MikroTik.”
Terry Combs Notes – Subnet Efficiency:
“Use /30 or /31 for point-to-point links. MikroTik supports /31 fully, unlike older systems.”
Answer: AQUESTION NO: 17 [Monitoring and Logging]
Which of the following protocols/ports are used for SNMP (Simple Network Management Protocol)?
A. TCP 25
B. TCP 161
C. UDP 162
D. TCP 162
E. TCP 123
F. UDP 161
Answer: C, F
SNMP uses UDP as its transport protocol. The standard ports are:
UDP port 161 → used for SNMP queries (polling)
UDP port 162 → used for SNMP traps (asynchronous alerts)
Incorrect options:
A. TCP 25 → SMTP (email), not related to SNMP
B. TCP 161 → SNMP does not use TCP
D. TCP 162 → Incorrect; SNMP traps use UDP
E. TCP 123 → NTP (Network Time Protocol)
Correct answers:
MTCNA Course – Monitoring Tools & SNMP:
“SNMP operates over UDP. Port 161 is used for polling, and port 162 is used for traps.”
René Meneses MTCNA Guide – SNMP Overview:
“SNMP uses UDP 161 and 162 for communication between manager and agents.”
Terry Combs Notes – Protocol and Port Summary:
“Remember: SNMP = UDP 161/162. Do not confuse with TCP-based protocols.”
Answer: C, FQUESTION NO: 18 [RouterOS Introduction]
Which of the following are valid IP addresses?
A. 10.10.14.0
B. 192.168.256.1
C. 192.168.13.255
D. 1.27.14.254
Answer: A, C, D
An IPv4 address is a 32-bit number divided into 4 octets. Each octet must be between 0 and 255.
Let’s evaluate:
A. 10.10.14.0 →✅Valid; .0 is legal, may represent a network or host depending on subnet
B. 192.168.256.1 →❌Invalid; 256 exceeds the max octet value (0–255)
C. 192.168.13.255 →✅Valid broadcast or host IP, depending on subnet
D. 1.27.14.254 →✅All octets are within valid range
MTCNA Training Manual – IP Basics:
“Each octet must be between 0 and 255. Addresses like 192.168.256.1 are invalid.”
René Meneses Guide – Valid IP Criteria:
“Watch for octets above 255 — they are illegal in IPv4.”
Terry Combs Notes – Address Format Validation:
“Decimal format must be checked — 256, 999, or negative values break IPv4 standards.”
Answer: A, C, DQUESTION NO: 19 [Routing]
The network address is:
A. The first address of the subnet
B. The first usable address of the subnet
C. The last address of the subnet
Answer: A
The network address is the first IP address in a subnet. It identifies the entire network segment and cannot be assigned to any host.
For example, in 192.168.1.0/24:
192.168.1.0 → Network Address (non-assignable)✅
192.168.1.1 – 192.168.1.254 → Usable host addresses
192.168.1.255 → Broadcast address
Clarifying:
A. First address of the subnet →✅Correct
B. First usable address →❌That would be second address
C. Last address of the subnet →❌That’s the broadcast
MTCNA Course Manual – Subnet Addressing:
“The first address in a subnet is reserved as the network ID. It cannot be assigned to a host.”
René Meneses Guide – Network and Broadcast Addresses:
“Network address = first IP in block, broadcast = last. Usable range lies in between.”
Terry Combs Notes – Host and Network Addressing:
“Always subtract 2 IPs: one for network and one for broadcast. Never assign .0 (network address) to a host.”
