ASN AS5721 is an Autonomous System Number used to identify a network for BGP internet routing.

Who manages ASN AS5721?

AS5721 is listed under National Defense University.

What do peers, upstreams, and downstreams mean in ASN data?

Peers are lateral network interconnections, upstreams are transit providers, and downstreams are customer networks receiving connectivity.

What are routes and IP ranges for an ASN?

Routes and IP ranges are the network prefixes announced by the ASN on the internet and show the address space it originates.

Why is WHOIS data shown for an ASN?

WHOIS data provides registration and contact context for ASN ownership, administration, and operational reference.

How can I access the full ASN tables?

The page shows a preview of large ASN datasets. Use the page controls to load more rows, and upgrade to a paid plan for complete access.

AS5721 National Defense University

ASN Lookup Tool

National Defense University ndu.edu

US 2 Routes

AS Data

AS5721

AS5721 – National Defense University

AS Number	5721
AS Name	NDU-NET
Organization	National Defense University(ndu-1)
Country	US
Website	ndu.edu
Number of IPv4 Routes	2
Number of IPv6 Routes	0
ASN type	EDUCATION
Registry	ARIN
Date Allocated	1995-09-06

ASN Intelligence API for production workflows

Use ASN data for AS5721 in automation: routing intelligence, peering analysis, ownership checks, and network observability.

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IP Ranges

Route	Origin	Origin Name	ISP	# IPs
216.21.18.0/24	AS5721	National Defense University	National Defense University	256
216.21.19.0/24	AS5721	National Defense University	National Defense University	256

Raw Whois Response

#
# ARIN WHOIS data and services are subject to the Terms of Use
# available at: https://www.arin.net/resources/registry/whois/tou/
#
# If you see inaccuracies in the results, please report at
# https://www.arin.net/resources/registry/whois/inaccuracy_reporting/
#
# Copyright 1997-2026, American Registry for Internet Numbers, Ltd.
#


ASNumber:       5721
ASName:         NDU-NET
ASHandle:       AS5721
RegDate:        1995-09-06
Updated:        2015-05-07
Comment:        http://www.ndu.edu    
Ref:            https://rdap.arin.net/registry/autnum/5721


OrgName:        National Defense University
OrgId:          NDU-1
Address:        Ft. McNair, Bldg. 62
City:           Washington
StateProv:      DC
PostalCode:     20319-6000
Country:        US
RegDate:        1994-10-04
Updated:        2015-05-07
Ref:            https://rdap.arin.net/registry/entity/NDU-1


OrgAbuseHandle: CJH19-ARIN
OrgAbuseName:   hartley, christopher john
OrgAbusePhone:  +1-202-685-4716 
OrgAbuseEmail:  chris.hartley.ctr@ndu.edu
OrgAbuseRef:    https://rdap.arin.net/registry/entity/CJH19-ARIN

OrgTechHandle: CJH19-ARIN
OrgTechName:   hartley, christopher john
OrgTechPhone:  +1-202-685-4716 
OrgTechEmail:  chris.hartley.ctr@ndu.edu
OrgTechRef:    https://rdap.arin.net/registry/entity/CJH19-ARIN

RNOCHandle: CJH19-ARIN
RNOCName:   hartley, christopher john
RNOCPhone:  +1-202-685-4716 
RNOCEmail:  chris.hartley.ctr@ndu.edu
RNOCRef:    https://rdap.arin.net/registry/entity/CJH19-ARIN

RTechHandle: CJH19-ARIN
RTechName:   hartley, christopher john
RTechPhone:  +1-202-685-4716 
RTechEmail:  chris.hartley.ctr@ndu.edu
RTechRef:    https://rdap.arin.net/registry/entity/CJH19-ARIN

RAbuseHandle: CJH19-ARIN
RAbuseName:   hartley, christopher john
RAbusePhone:  +1-202-685-4716 
RAbuseEmail:  chris.hartley.ctr@ndu.edu
RAbuseRef:    https://rdap.arin.net/registry/entity/CJH19-ARIN


#
# ARIN WHOIS data and services are subject to the Terms of Use
# available at: https://www.arin.net/resources/registry/whois/tou/
#
# If you see inaccuracies in the results, please report at
# https://www.arin.net/resources/registry/whois/inaccuracy_reporting/
#
# Copyright 1997-2026, American Registry for Internet Numbers, Ltd.
#

Parsed Whois Response

Peers

AS Number	Description	Country
AS22773	Cox Communications Inc.	US
AS33657	Comcast Cable Communications, LLC	US

Upstreams

AS Number	Description	Country
AS22773	Cox Communications Inc.	US
AS33657	Comcast Cable Communications, LLC	US